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            Argus A2B         to list of articles

     ©Infotech 2004

Caution: This article is provided for information purposes only. Neither Infotech nor the author can be liable for any damage caused when following these instructions. Success in camera repair depends on the skill of the technician. If you're new to camera repair, please practice on equipment that has no value before working on a unit you want to save. We have checked the article for errors. However, if there are errors we didn't catch, the extent of our liability is to correct such errors when we learn about them.

                Operation
                Removing the shutter
                Shutter operation
                Shutter disassembly
                Reassembly
 

When Argus introduced the Model A in 1936, 35mm photography became a popular and affordable hobby—the Model A sold for under $10. The Model A2B, introduced in 1940, added an extinction exposure meter to the basic design, Fig. 2. Although the A-series Argus cameras hold an important place in photographic history, the black plastic models don't as yet have great monetary value. The model A's in a brass finish (gold colored) or chrome finish have much more value because of the limited production.

OPERATION
Lens Barrel. The lens barrel has two positions. Fig. 1 shows the lens barrel in the collapsed position. Here three lugs at the back of the lens barrel fit under three tabs on the front plate, holding the lens barrel against the tension of an internal spring.

For the extended picture-taking position, rotate the lens barrel until the three lens-barrel tabs clear the three front-plate lugs. A spring now pushes forward the lens barrel, Fig. 2. Rotate the lens barrel to the position shown in Fig. 2 with the Argus name to the top; you'll feel a click when the lens barrel reaches the proper rotational position.

Shutter. The camera uses an Ilex shutter. Pushing the release lever, Fig. 2, both cocks and releases the shutter. For speed control, the shutter uses a mechanical governor controlled by the speed cam, Fig. 2. The iris diaphragm sits behind the shutter blades; set the aperture with the aperture-control lever, Fig. 2.

Extinction exposure meter. The extinction exposure meter uses a scale and calculator, Fig. 3, to determine the exposure settings. The light passes through a series of openings—the openings get progressively larger. The higher the light level, the smaller the opening through which you can see light.

In use, look through the openings at the back of the camera, Fig. 4. Then move the calculator, Fig. 3, until its tab, Fig. 4, is over the smallest opening through which you can see light. The lower the light level, the further to the left, Fig. 4, you'll have to move the calculator.

The left-hand edge of the calculator aligns with the edge of one of the scale columns, Fig. 3. Now move the slider of the calculator (the piece with the diaphragm calibrations) until its arrow, Fig. 3, aligns with the type-of-day rows (bright, average, etc.) on the scale. In Fig. 3, the arrow aligns with the "bright" column, the proper setting for a bright light level. You can then use one of the aperture/shutter-speed calibrations that align horizontally. For example, in Fig. 3 you could use an aperture of 6.3 with a shutter speed of 1/150 second, an aperture of f/9 with a shutter speed of 1/100 second, an aperture of f/12.7 with a shutter speed of 1/50 second, or an aperture of f/18 with a shutter speed of 1/25 second.

Film Advance.  Install the film cartridge at the right-hand side of the camera, Fig. 4. Slip the end of the film leader into the slot in the take-up spool. As you turn the film-advance knob at the top of the camera, the take-up spool draws the film from right to left, wrapping the film around the take-up spool. The film turns the sprocket, Fig. 4. When the sprocket has turned far enough for the next film frame to be in position, a latch stops the sprocket gear--you can see the sprocket gear and the counter gear above the sprocket, Fig. 4.

With a modern 35mm camera, the sprocket disengages when you release the shutter. But there's no such linkage in the A2B. After you shoot the picture, disengage the sprocket by pushing the sprocket latch, Fig. 1. You can now turn the film-advance knob to advance the film. After you've finished the roll, rewind the film by turning the rewind knob, Fig. 1, in the direction of the engraved arrow; the sprocket turns freely in the rewind direction.

The counter does not return to the start position on its own. Just turn the counter dial to align the "0" with the index. Rather than coupling directly to the counter gear, the counter dial sits above a pressure spring. The pressure spring couples the counter dial to the counter gear (the gear turned by the sprocket gear). But you can manually turn the counter dial against the resistance of the pressure spring.

Note: If you do want to remove the counter dial, hold the sprocket to prevent the counter dial from turning. Then remove the screw holding the counter dial. Watch for the loose parts—the flat pressure spring and a brass collar that sits above the counter gear. The counter gear may drop below the sprocket gear. On reassembly, hold up the counter gear and make sure it's engaged with the sprocket gear.

REMOVING THE ILEX SHUTTER
You can perform most repairs without removing the shutter from the camera. That's a big advantage—removing the shutter isn't always easy. A retaining ring, Fig. 4, holds the shutter. But the narrow confines of the film aperture make it difficult to reach and unscrew the notched retaining ring. The retaining ring has two pairs of notches—one pair should then be accessible.

You may have to tilt the tips of your spanner as described in General Repair Tips. Some technicians use a pair of long needle-nose pliers with the tips cut to fit the retaining-ring notches. Hold the lens barrel to prevent it from turning. Then unscrew the retaining ring. Watch for the loose spacer at the back of the shutter.

It's easier to reach the retaining ring if you first take out the lens barrel. But removing the lens barrel, Fig. 5, introduces some new concerns. To remove the lens barrel, take out the four screws holding the front plate (the shiny metal plate through which the lens barrel passes). Now the coil spring—the spring that pushes the lens barrel to the extended position—may cause a problem. If you remove the four front-plate screws and then lift out the lens barrel, the coil spring stays with the lens barrel. The lower end of the coil spring may then catch and pull loose the felt light trap in the camera body.

You can avoid pulling loose the felt if you leave the coil spring in the camera body. After you remove the four front-plate screws, let the coil spring push up the lens barrel, Fig. 5. Then reach behind the lens barrel with your tweezers and grasp the coil spring. Hold down the coil spring as you lift out the lens barrel, Fig. 5. Now the coil spring and the light trap should stay in the camera, Fig. 6. Fig. 7 shows the lens-barrel assembly removed from the camera body.

Reassembly presents another problem—you may have trouble passing the lens barrel between the felt and the coil spring without pulling loose the felt light trap. The lower edge of the lens barrel likes to catch the felt light trap, pulling the felt light trap loose from the camera body. If the felt light trap does come loose, cement it to the inside of the camera body, Fig. 6; you can use Pliobond or a similar cement. You don't have to cement the entire area. But make sure you've cemented the front edge of the felt light trap—if the front edge comes loose from the camera body, either the spring or the lens barrel will catch that edge on reassembly. You'll get the most secure bond if you contact-cement the felt light trap. That is, apply the cement to both the inside of the camera body and the back of the felt light trap.

Carefully seat the coil spring with the larger end toward the camera body, Fig. 6; you may have to slip in the coil spring at a slight angle to avoid pulling loose the felt light trap. Next seat the lens barrel, Fig. 7, over the coil spring—make sure the shorter flat on the front plate faces the top of the camera. Again be very careful to avoid pulling loose the felt light trap with the rear edge of the lens barrel. You can watch through the film aperture to make sure the felt light trap remains in place as you push in the lens barrel. Push in the lens barrel until the front plate will seat on the camera body. Then replace the four screws that hold the front plate.

You can see the advantages of leaving the shutter on the camera body. If you do remove the shutter, the lug plate, Fig. 8, is loose. The lug plate, the plate with the three lugs that pass behind tabs on the front plate, sits at the back of the shutter. The slot in the lug plate fits over the shutter-locating pin—the shutter-locating pin also passes through a slot at the front of the lens barrel. We've removed the shutter for the following illustrations. But you can perform most of the disassembly without removing the shutter.

SHUTTER OPERATION
If you're not interested in the explanation of the operation, skip ahead to Shutter Disassembly. To see how the speed cam controls the operation, unscrew the front lens cell. Then remove the nameplate at the front of the shutter (two screws).

Fig. 9 shows the cam slots in the speed cam. The cam slot over the retard-lever tab controls the depth of retard-lever engagement. When the shutter blades near the full-open position, the retard lever then slows down the operation. The greater the depth of retard-lever engagement, the slower the shutter speed. At the two fastest shutter speeds (1/100 and 1/150), the retard lever doesn't delay the operation at all; the main lever moves unrestricted to open the shutter blades.

Spring tension determines the difference between 1/100 second and 1/150 second. At 1/150, the high-speed lobe on the speed cam, Fig. 9, comes against the mainspring-control lever. The speed cam then pushes the mainspring-control lever in a counterclockwise direction. One end of the mainspring connects to the mainspring-control lever. So, as the mainspring-control lever moves counterclockwise, it increases the tension of the mainspring. The main lever travels faster, increasing the blade-opening speed.

Lift off the speed cam, Fig. 9. When you now operate the shutter, you should get time operation with full retard. Next remove the cover plate by taking out its two screws, Fig. 10. You can still operate the shutter to study the operation, Fig. 11. Again, the shutter should deliver time operation with full retard.

The release lever pushes the main lever in a clockwise direction. The right-hand end of the main lever then passes up and over the sloped tab on the leaf lever, Fig. 11 (leaf lever is the National Camera term for the part that couples to the blade-operating ring—the leaf lever drives the blade-operating ring in both the opening and closing directions).

Once the main lever reaches the left-hand side of the leaf-lever tab, it' s released by the release lever—the release lever moves past the left-hand end of the main lever. Now the mainspring drives the main lever counterclockwise. The right-hand end of the main lever picks up the leaf-lever tab, driving the leaf lever clockwise. Moving in a clockwise direction, the leaf lever opens the shutter blades—the slot in the leaf lever fits over a post on the blade-operating ring, Fig. 12.

Most blade-type shutters apply the retard action to the main lever. But the Ilex shutter slows down the leaf lever for different shutter speeds. A tab on the leaf lever strikes the retard lever, Fig. 12. With full retard, the blades nearly reach the full-open position when the leaf lever strikes the retard lever. The leaf lever then has to push the retard lever against the resistance of the slow-speed governor. Fig. 12 shows the parts with the shutter fully open; the leaf lever must continue pushing against the retard ever with the blades in the full-open position.

As you set faster shutter speeds, the speed cam pushes the retard-lever tab toward the outside of the shutter. The gap between the retard lever and the tab on the leaf lever then increases. Now the leaf lever strikes the retard lever later in the cycle—and has to drive the retard lever a shorter distance—for a faster shutter speed.

At the 1/100-second setting, the speed cam holds the retard lever out of the leaf lever's path. The shutter operates as fast as it can with no retard action. But there's a faster speed yet—1/150 second. Here the lobe on the speed cam comes against the mainspring-control lever, Fig. 13. The speed cam pushes the mainspring-control lever counterclockwise. One end of the mainspring connects to the mainspring-control lever. Pushing the mainspring-control lever counterclockwise increases the mainspring tension for a faster shutter speed.

With the speed cam removed, the shutter should also deliver time operation. Fig. 13 shows the shutter held open on time. Here the main lever has opened the shutter blades. But the release lever can't return to its start position—the left-hand end of the time/bulb lever blocks a tab on the release lever. Also, the right-hand end of the time/bulb lever blocks a main-lever tab, Fig. 14. Since the main lever can't move past the lug on the leaf lever, the blades stay open.

For time operation, the speed cam allows the time/bulb lever full movement. The left-hand end of the time/bulb lever then moves far enough to block the release lever. When you push the release lever a second time, the release-lever tab comes against the end of the disengaging lever, Fig. 13. The disengaging lever, pushed from left to right by the release lever, disengages the time/bulb lever from the main lever. The main lever now completes its stroke, freeing the leaf lever to close the shutter blades.

For bulb operation, the speed cam limits how far the time/bulb lever can move. Here, the time/bulb lever moves far enough to block the main lever—but it doesn't move far enough to block the release lever. The shutter then stays open for as long as you hold down the release lever. When you let the release lever return, the release-lever tab comes against the left-hand end of the time/bulb lever. The release lever then pushes the time/bulb lever out of engagement with the main lever.

At instantaneous speeds, the speed cam blocks the movement of the time/bulb lever. The time/bulb lever then plays no part in the operation.

SHUTTER DISASSEMBLY
If you've followed through the section on operation, you've already completed the first steps of disassembly. Here's the complete sequence:

1. Unscrew the front lens cell.
2. Remove the nameplate at the front of the shutter (two screws).
3. Lift off the speed cam, Fig. 9.
4. Remove the cover plate, Fig. 10 (two screws).
5. Remove the cable-release socket, Fig. 13 (one screw at the outer circumference of the shutter housing).
6. Disconnect the time/bulb-lever spring from the tab on the disengaging lever, Fig. 13.
7. Remove the shoulder screw holding the time/bulb lever, Fig. 13 (the spring stays with the screw). Lift out the time/bulb lever.
8. Disconnect the release-lever spring from the tab on the release lever.
9. Remove the screw holding the release lever, Fig. 15 (the spring stays with the screw).
10. Remove the release lever by sliding it toward the center of the shutter. Tilt the release lever as necessary to pass the end through the housing slot.

Note: It's possible to reach the shutter blades without removing the slow-speeds governor, the leaf lever, or the main lever. However, if the shutter blades appear to be clean, you may prefer to leave the shutter blades and the mechanism plate in the shutter. You can then take out the slow-speeds governor, the leaf lever, and the main lever for individual cleaning. But if you want to reach the shutter blades, you can just remove the two L-shaped brass screw lugs, Fig. 17 (each is held by one screw at the outer circumference of the shutter housing), and the two screws holding the mechanism plate. If you want to remove the individual parts, proceed as follows:

 
11. Disconnect the retard-lever spring from the tab on the retard lever, Fig. 15.
12. Remove the two screws holding the speeds-governor bridge, Fig. 15—the shoulder screw also retains the retard-lever spring which is now loose.
13. Lift off the speeds-governor bridge, Fig. 15—the parts of the slow-speed governor are now loose, Fig. 16.
14. Lift out the pallet (sometimes called the anchor), the star wheel, and the retard lever, Fig. 16.

Note: The slow-speed governor is also called an escapement, a term from the watch and clock industry. As the star wheel turns, it has to rock the pallet back and forth. The leaf lever must then push the retard lever against this resistance. The very short gear train can only provide a slowest shutter speed of 1/25 second. Shutters with slower speeds just add gears between the retard lever and the star wheel. One second is normally the slowest practical shutter speed with a mechanical slow-speed governor.

15. Remove the two L-shaped screw lugs, Fig. 17 (the screw lugs provide the screw holes for the cover-plate screws). Each screw lug is held by one screw at the outer circumference of the shutter housing).
16. Disconnect both ends of the leaf-lever spring—one end from the leaf lever and one end from the post, Fig. 17.
17. Remove the leaf-lever screw and spring.
18. Disconnect both ends of the mainspring—one end from the mainspring-control lever and the other end from the main-lever tab.
19. Remove the screw holding the mainspring-control lever, Fig. 17. Lift off the mainspring-control lever, the spacer washer, and the mainspring.
20. Lift out the main lever and the brass spacer washer that sits under the main lever.
21. If the shutter blades appear to be clean, you may not want to go further in the disassembly. You can clean the surface of the mechanism plate with a tissue moistened with alcohol. Or, if you did remove the shutter, unscrew the rear lens cell; then clean the shutter in a cleaning machine. But if the shutter blades are dirty, you may want to remove the mechanism plate; the shutter blades remain with the mechanism-plate assembly. Scribe the position of the mechanism plate, Fig. 18, with respect to the inside of the shutter housing. The scribe lines will help you seat the mechanism plate in the proper rotational position.
22. Remove the two screws holding the mechanism plate, Fig. 18.
23. Lift out the mechanism plate together with the shutter-blade assembly. The mechanism plate has a tight fit. Sometimes it helps to insert a screwdriver or tweezers through the slots in the shutter housing; then pry up with the tool to lift a portion of the mechanism plate. Be gentle—you can't get replacement parts.
24. The blade-cover plate that holds the shutter blades in place mounts to the back of the mechanism plate, Fig. 19. Scribe the position of the blade-cover plate with respect to the blade-base plate (the black plate under the blade-cover plate in Fig. 19—you can reach the blade-base plate through one of the cutouts in the blade-cover plate). The blade-cover plate can only go in one position. But that position can be difficult to locate. Put one scribe line on the blade-cover plate and a matching scribe line on the blade-base plate. On reassembly, just match the scribe lines. Besides showing you the proper rotational position, the scribe line on the blade-cover plate shows you which side goes up. Also scribe the positions of the screws holding the blade-cover plate, Fig. 19. With so many holes in the blade-cover plate, the scribes marking the screw positions can speed up reassembly.
25. Remove the screws holding the blade-cover plate.
26. Lift off the blade-cover plate. Note the positions of the three shutter blades, Fig. 20.
27. Remove the shutter blades. Be careful when handling the shutter blades—they are made of hard rubber. If you use a solution to clean the shutter blades, stick with isopropyl alcohol.
28. The blade-base plate, Fig. 20, can only go in one position. But, as with the blade-cover plate, that position can be a problem to locate. One reference you might use is the position of the post on the blade-operating ring (the post engaged by the leaf lever), Fig. 18. In Fig. 20, we've positioned the post at a 12 o'clock position. We've then scribed the blade-base plate with an arrow pointing to the blade-operating-ring post. Once you've noted the position for reassembly, lift off the blade-base plate.
29. Lift out the blade-operating ring, Fig. 21.

REASSEMBLY

Lubrication: Some technicians say that the Ilex shutter doesn't need lubrication. Certainly no lubrication is better than too much lubrication. However, we'll point out the normal lubrication points for this type of shutter. Proper lubrication does minimize wear and provide smoother operation.  Above all—never use oil in a blade-type shutter. Oil will eventually work its way to the shutter blades. Moly-lube makes a good grease lubricant. Dry moly provides a good dry lubricant that's not abrasive.

You may want to lubricate the blade-operating ring and its track on the mechanism plate with dry moly. Rub the dry moly into the blade-operating-ring track on the back of the mechanism plate. Then blow off the excess. Also rub the dry moly into the front surface of the blade-operating ring. Again blow off the excess.

1. Seat the blade-operating ring on the back of the mechanism plate, Fig. 21. The post on the blade-operating ring passes through the mechanism-plate slot.
2. Replace the blade-base plate, Fig. 20, according to your scribe lines. Or refer to Fig. 20—here the post on the blade-operating ring is at a 12 o'clock position.
3. You can replace the shutter blades in either the opened or the closed position. Position the mechanism plate with the post on the blade-operating ring at around a 12 o'clock position, Fig. 20. Seat the first shutter blade as shown in Fig. 20. Replace other two shutter blades in a counterclockwise rotation.
4. Replace the blade-cover plate according to your scribe lines, Fig. 19. Replace the screws holding the blade-cover plate.
5. Seat the mechanism-plate assembly in the shutter housing as shown in Fig. 18. Match your scribe lines for the rotational position—the two screw holes should now align. Replace the two countersunk screws.

Test. Check the freedom of the shutter blades by moving the post on the blade-operating ring, Fig. 18. When you move the blade-operating ring in a counterclockwise direction, the blades should smoothly and freely open.

6. Replace the leaf lever with its slot over the post on the blade-operating ring, Fig. 17. Replace the screw that holds the leaf lever (the leaf-lever spring remains seated in the groove under the screw head). Connect the short end of the leaf-lever spring to the leaf-lever tab; connect the long end of the leaf-lever spring to the groove in the mechanism-plate post, Fig. 17.

Test. Check the blade operation by moving the leaf lever clockwise to open the shutter blades. When you release the leaf lever, the leaf-lever spring should snap the shutter blades to the closed position.

You can lightly lubricate the post for the main lever with a thin film of shutter grease such as moly-lube. Lubricating the post minimizes wear—both in the main lever and in the post. However, since the shutter probably won't see much use, wear may not be a major concern.

7. Seat the large brass spacer washer over the main-lever post.
8. Seat the main lever above the spacer washer, Fig. 17.
9. Seat the mainspring on top of the main lever—the short end of the mainspring goes up.
10. Seat the second spacer washer above the main lever.
11. Replace the mainspring-control lever and the screw as shown in Fig. 17.
12. Connect the short end of the mainspring to the notch in the mainspring-control lever. Connect the long end of the mainspring to the main-lever tab, Fig. 17.

Test. Check the operation by moving the left-hand end of the main lever in a clockwise direction—the right-hand end of the main lever slides up and over the sloped tab on the leaf lever. Then let go of the main lever. The mainspring should drive the main lever counterclockwise.

Use shutter grease to lubricate the right-hand end of the main lever—the leading main-lever edge that comes against the straight edge of the leaf-lever tab. Also put a light film of shutter grease on the sloped side of the leaf-lever tab.

13. Replace the two screw lugs, Fig. 17. The screws that hold the screw lugs pass from the outside of the shutter housing. You can leave the screws slightly loose for now—later you'll shift the screw lugs to align their screw holes with the holes in the shutter-cover plate.

Since the gear train of the slow-speed governor is so short, dry-moly lubrication should not be necessary. Most slow-speed governors are self-contained—you remove and replace the slow-speed governor as a complete unit. You can then use dry moly to lubricate the slow-speed governor as described in our article on lubrication (blow the dry moly into the gear train, work the retard lever a few times, and blow out the excess). Never blow the dry moly into the gear train when the slow-speed governor is installed in the shutter—the dry moly may settle on parts you don't want to lubricate, such as the shutter blades. You could lubricate the slow-speed governor in the Argus shutter by first putting some dry moly on a cotton swab. Use the cotton swab to rub dry moly into pivot holes on the mechanism plate and the pivot holes in the speeds-control bridge. Blow off the excess dry moly. Also use the cotton swab to rub dry moly into the tips of the pallet that engage the star wheel. Again blow off the excess before you replace the pallet.  Use shutter grease to lubricate the edge of the retard lever (the edge that's struck by the tab on the leaf lever).

14. Seat the pallet, the star wheel, and the retard lever as shown in Fig. 16.
15. Seat the speeds-governor bridge, Fig. 15. Shift the pallet, star wheel, and retard lever as necessary until the upper pivot of each part passes through its pivot hole in the speeds-governor bridge. When the speeds-governor bridge seats fully, replace the smaller screw at the pallet end.
16. Place the retard-lever spring with its coil over the screw hole for the larger speeds-governor-bridge screw. Make sure the spring is right side up—the tip at the longer spring end points down, toward the shutter (this end connects to the hole in the speeds-governor bridge).  Replace the larger screw for the speeds-governor bridge with its shoulder passing through the coil of the retard-lever spring. Make sure the spring coil isn't pinched by the screw.
17. Connect the long end of the retard-lever spring within the hole in the speeds-governor bridge, Fig. 15. Connect the short end of the retard-lever spring to the tab on the retard lever, Fig. 15.

Test: Again push the left-hand end of the main lever in a clockwise direction. Then release the main lever. The main lever should now drive the leaf lever against the resistance of the retard lever. The shutter blades should close after the brief exposure. If the shutter hangs open, check for a bind in the slow-speed governor. Push the retard lever counterclockwise. The retard lever should move smoothly and easily. When you release the retard lever, the spring should return the retard lever to the start position, Fig. 15.

18. Slide the release lever through the slot in the shutter housing—from inside the shutter to the outside of the shutter, Fig. 19. Replace the release-lever screw (the release-lever spring should still be seated within the groove of the release-lever screw). After you tighten the release-lever screw, check to make sure the release lever moves freely. Connect the release-lever spring—the short end to the release-lever tab, the long end to the inside of the shutter housing, Fig. 15.

Test: Check for normal operation by actuating the release lever. The shutter should release, providing the 1/25-second shutter speed. When you let go of the release lever, the spring-driven release lever should return to its start position—the end of the release lever pushes up the end of the main lever as the release lever returns.

Use shutter grease to lubricate the left-hand end of the main lever—lubricate the lower side where it's engaged by the release-lever tab. Also apply shutter grease to the top of the release-lever tab (the side that has to slide under the main lever on the return stroke of the release lever).

20. Seat the time/bulb-lever assembly, Fig. 13. Replace the shoulder screw with the spring. Connect the long end of the time/bulb-lever spring to the tab on the disengaging lever. The other end of the time/bulb-lever spring just presses against the inside of the shutter housing.

Test: Make sure the time/bulb lever and the disengaging lever move freely. Check the operation by pushing the release lever. The shutter should deliver time operation with full retard.

21. Replace the cable-release socket, Fig. 13, from the outside of the shutter housing. The slot in the cable-release socket straddles an extension of the release lever. Replace the screw from the outside of the shutter housing.
22. Replace the cover plate as shown in Fig. 10. Notice the clearance cutouts for the time/bulb-lever tab, the mainspring-control lever, and the retard-lever tab. Work through the screw holes in the cover plate to align the screw holes on the brass screw lugs (since we left the screws for the screw lugs slightly loose, you can shift the screw lugs for proper alignment with the cover-plate holes). Then replace the two cover-plate screws. Now you can firmly tighten the screws for the screw lugs. Check the operation—you should still get time operation with full retard.

Lubricate the end of the time/bulb lever that engages the main lever, Fig. 14, with shutter grease. Also use grease to lubricate the release-lever tab—both on the side that comes against the disengaging lever and the side that comes against the left-hand end of the time/bulb lever.

Also grease-lubricate the inner circumference of the speed cam—the inner edge that rides against the cover plate. The speed cam then turns more smoothly. You can adjust the pressure required to turn the speed cam by bending the speed-cam section that controls the time/bulb lever (toward the center to increase the pressure, away from the center to decrease the pressure). However, you should make every effort to avoid bending any part. If a part breaks, you'll have trouble finding a replacement.

23. Make sure the speed cam is right side up (compare with Fig. 9). As you replace the speed cam, be careful to avoid bending the tabs on the time/bulb lever, the main-spring-control lever, and the retard lever--make sure these tabs pass through the speed-cam slots and ride against the edges of the speed cam. When you're sure all three tabs are cleared by the cutouts, fully seat the speed cam.

Lubricate the cam edges of the speed cam—the edges against which the tabs ride—with shutter grease. Also lubricate the speed-cam lobe that comes against the mainspring-control lever at 1/150 second. The speed cam should then turn more smoothly.

24. Replace the nameplate with its two screws. Check the operation at all speed-cam settings.

Note: Adjustments require bending the tabs on the control levers—as we keep stressing, avoid bending a tab if at all possible. For example, perhaps the shutter delivers proper time operation. But on bulb, you get an instantaneous shutter speed. You may have to slightly bend the tab on the time/bulb lever away from the speed cam. The time/bulb lever can then move further toward the center of the shutter. Or perhaps you get time operation at the bulb setting. It may then be necessary to bend the tab on the time/bulb lever toward the speed cam, limiting the movement of the time/bulb lever a little more. Never bend a tab unless you're sure it's necessary. And be very careful to avoid bending a tab too far. If you bend the tab back and forth too many times, it will surely break.

If you do decide to bend a tab, use a strong pair of tweezers. Grasp the tab with the tweezers. Then gently tilt the tweezers in the direction you want to bend the tab. Test the operation after each bend. This way you can make the adjustments in small increments and avoid overshooting the proper tab position

With many shutters, bending tabs provides the shutter-speed adjustments. With the Argus shutter, bending the retard-lever tab away from the speed cam provides deeper retard engagement for a slower shutter speed. But with antiques, bending a tab presents too big a risk. The tab may break, and you usually can't replace parts unless you can find another shutter. Shutter-speed accuracy isn't as critical as proper operation.

25. Screw on the front-lens group to complete the reassembly.