I recently started having problems with my shutter again. It seems like even after the previous repair (mentioned here) and a further attempt to glue back the light seal by opening up the camera, the problem has not gone away. It did work for weeks, but it has now returned. It may also have something to do with the increasing humidity as a result of the onset of summer. By the way, I don’t recommend removing the body cover of the camera without removing the top (shown below) because it will result in much contortion and bending of metal. Not fun.
Now what else could I do? Like any good engineer I tried to diagnose the issues. Firstly, I noticed that the shutter always got stuck after sitting around for a long time, cocked. If it sat around uncocked, it does not affect the movement. Secondly, the frames were almost always overexposed on one half, and properly exposed on the other. In other words, whatever is causing the shutter to get stuck is probably preventing the shutter curtain from moving freely along its track. The first suspect (which was dealt with) was the light seal, and that in fact probably was at least part of the cause. Thirdly, the increased severity of the problem with increased humidity and temperature suggests it may have something to do with adhesives, which tend to turn gross and gummy in the heat and high humidity. Again, the glueing of the light seals seems to be a prime candidate. I figured, maybe the light seal came off again. Having no recourse, I proceeded to open up the top of the camera for the first time.
As a side note, opening up the top turned out to be relatively easy, once you have the right tools. In addition to the regular screwdriver set, tweezers and spanners, you need a set of wrenches from Micro-Tools, which allow the removal of all the parts without damaging the camera. Instructions for the disassembly can be found online with some effort (I refer to a combination of three manuals to disassemble/reassemble the camera). I resisted opening up the bottom because it will involve some yanking and flexing, and also because it meant that the rangefinder would have to be re-aligned. After opening up the whole camera, I went about looking for some clue as to the causes of slow shutter movement.
Inspection of the light seals revealed no signs of de-bonding or gumminess, so out went the only working theory. I was reminded that, in an old reply on rangefinderforum, someone having a similar problem mentioned that DAG, the famous repair person/group cited an improperly glued curtain as the cause. Since the curtains are glued onto the drum via a couple of ribbons, I checked to make sure the ribbons are clean (which they were). There was one stray thread that may conceivably get caught in the gear mechanism, though I consider that unlikely. I removed it with my trusty X-Acto knife regardless. The drum was in pretty good shape, and there appeared to be no residual glue on the crimped curtain end. At this point, I noticed that there was a funny pattern on my second curtain. Closer inspection revealed that the pattern corresponded to the curtain clamp highlighted below.
Again, since the problem only surfaced when the camera was sitting wound, and the rear curtain actually gets wound around the drum, compressed against this piece, the pattern I am seeing may have been indicative of grease, oil or adhesives sticking to the curtain. I touched the drum and found that there was indeed a tiny bit of stickiness to it. Now, I am not sure if this was in fact the problem, but given that there was detectable stickiness, that the curtain is tightly-compressed against this part, and that the problem only surfaced with long periods of inactivity, it was the best explanation I had. So I cleaned up this part with a little rubbing, and, perhaps a little foolishly, stuck a new piece of 3M tape on the drum so that the back of the tape was in contact with the curtain. This is holding now, but I really wonder what would happen when the tape disintegrates into a gummy mess.
So far, after applying the fix, I’ve yet to have any recurrence of the problem. Let’s hope this will solve my problem once for all!