Film cameras are not serviced any more and as time goes by the condition you find them in when you collect them gets worse and worse. Nowadays, when I acquire a film camera, I typically find it in need of some (or a lot of) cleaning and/or restoration work, such as:
... and I haven't even mentioned the lens. Lenses are yet another (BIG) story.
Here we have a Mamiya MSX 500 camera that came to me in a rather poor shape. (The MSX 500 is a member of a family of Mamiya 35mm SLRs with 'brothers' and 'sisters' like the MSX 1000 and the DSX 1000. Most of the things I say here about the MSX 500 are applicable to these other cameras, as well.)
Before I wind up and release the shutter I always do an inspection of the film compartment, the shutter curtains, and the mirror chamber. I look for crumbling foam, soiled or wrinkled shutter curtains, and a stuck mirror. Releasing the shutter could make things worse, if there are problems in these areas. Almost always I end up having to remove the old foam. If you read this, you probably have already seen the yucky, gooey stuff old foam tends to turn into. The sooner it is gotten rid of is the better, because once it gets on the shutter curtains or optical parts it is hard to clean off.
I don't have a magic trick for removing foam seals - I just scrape them out with toothpicks or a screwdriver. Some solvents might help, but the glue is usually damn tough. It is a tedious job, but must be done. For a replacement in the film compartment I don't use anything else but knitting wool and strips of velvet. I could buy new foam, but would I want my cameras to exhibit the same old problem in twenty years time? No way! I don't understand why even famous brand name manufacturers of more recent decades stuck to using this horrible sinthetic stuff. Fabric, on the other hand, lasts forever. In actual fact, in really old cameras this is what one finds and there is no problem with it. Now, the mirror damper is another matter. Having not found an acceptable substitute, I buy the product MicroTools sells. (Yes, it is foam with a self adhesive backing.)
Check the battery compartment for a leaking old battery. Even if the battery is good, don't leave it in the camera when you put it down for a while with the intention to come back to it later. It tends to be forgotten. Products are available for cleaning electrical contacts. Most of them come in spray cans, which are of little use, but I found a good liquid called DeoxIT (by CAIG Laboratories Inc.) which is sold in a small bottle.
When a camera is in such a poor state as my Mamiya MSX 500 some disassembly is unavoidable to get to the other parts that need attention. So, let 's begin with taking off the camera's top.
This is a little bit tricky. Beginning with the film advance lever, what you would normally do is to unscrew the decorative disc that holds down the lever. You need to use a piece of rubber to do this, as there is no slot for a screwdriver. The first catch is that this disc unscrews clockwise instead of anticlockwise. However, it is also secured by a set-screw, which is hidden under the light meter switch push-button. So, first this button has to be taken out. Notice the leather cover on the button - stick a suitable tool under it as if beginning to peel it off and grabbing it that way pull up the button. If the leather patch is missing or came off when you pulled, you will see two holes in the button. You can get access to the set-screw through one of these holes. Find the set-screw and unscrew it. Now you can remove the shiny disc (or collar) that holds the lever in its place by turning it clockwise. (Note: if in your camera version you don't have holes in the push-button, then there is a somewhat more complicated way to remove it which involves taking off the bottom plate. I will write about this later.)
Mamiya's cluey engineers equipped the shutter selector / film speed dial knob with a puzzle, as well. You solve the puzzle by setting the ASA dial onto the 80 mark thereby uncovering a secret hole on the side of the knob. This gives you access to the set-screw that you need to take out to be able to remove the knob. (This is a very long screw.) However, before you do that, set the shutter speed selector to 'B' (and keep it that way until you finish). Be careful, when you lift off the knob; there is a pin under there at the end of a spring loaded chain which connects the shutter speed selector with the light meter indicator. Hold that pin with a toothpick as you lift off the knob and release it gently afterwards.
The shutter selector knob can be further disassembled for cleaning but it is risky to do so. You need to pry off the top plate that has the shutter speed numbers printed on it. This plate is made of soft metal and gets easily marked. Once damaged, it will severely degrade the cosmetic appearance of the camera, so think twice before you start messing with it. It is glued down in the middle with shellac, so you can use methylated spirits to soften the shellac first. Let the fluid flow under through the ASA and DIN scale windows. Then carefully stick a pin or a thin blade between the disk's edge and the knob's perimeter and try to lift up. The next picture shows what you find underneath. The thin metal piece in there acts like a spring when you pull up the knob to set the film speed. To see this at work now, you need to take hold of the narrow ring at the bottom while pulling the rest of the knob up. (Not easy.)
What I did next was to remove the camera front. The lens mount was loose and appeared to be warped. Later I discovered that the mounting ring was in fact straight, but the three springs(!) and the unevenly tightened screws gave it a bent appearance. Springs in the mounting ring? What a novel idea. I have not been able to figure out what purpose they are meant to serve.
The black plastic front cover is secured by two screws at the bottom. As you separate the cover from the body, take care that it does not crack near the flash sockets. The plastic is thin there. The lens mounting ring is held by four screws and there are four U shaped washers (or shims) underneath. Don't lose them. You will find that the lens mount has two parts; a ring with the three springs I mentioned earlier, and a threaded ring. Interesting.
You will also find a spring loaded pin on the left side (as you face the camera), which is also a means to ensure that the lens is correctly mounted. The thin metal ring around the front opening plays a role in determining the correct exposure - see if you can figure out how this works. In case you lost track of it, the picture below shows how the inner ring with the strange cut-outs fits over the camera body.
The next task is to remove the penta-prism. Surprisingly, it is only held in position with a piece of wire over the top of it. The challenge here is to unhook and remove the tight wire without damaging the black coating on the prism. If you examine the metal frame where the two ends of the wire are attached you see not holes, but things like a pair of bent fingers. So, you can push the wire ends out in a forward direction.
The metal frame in which the prism sat can be taken out after removing four screws. Below this there is a very thin and delicate frame with the + / - markings for the light meter's needle. Handle it carefully (and as little as possible).
Finally, we got to the focusing screen. This camera presents a somewhat unusual solution in this area, as well. In many cameras the focusing screen is at a fixed distance from the mirror. In some, the distance can be adjusted and the focusing accuracy (as seen through the viewfinder) fine-tuned. The Mamiya MSX 500 falls into this latter category. (The Minolta SRT 101 is like this, too.) The trouble is that if you disturb the setting it is hard to put it back without a suitable measuring equipment. You will see three screws which are not screwed in fully and are painted over signalling that they must not move. The focusing screen is actually pushed upwards by a slightly bent metal frame bellow it, which acts like a spring. What I did was to measure the gap below the screw heads and then went ahead and took out the three screws. Admittedly, this is not a very accurate way of going about this, but let 's be honest; what are the chances that this camera will ever be used again for serious photography? I think the answer is nil. (If this approach makes you crunch, ask yourself the question; how many rolls of film did you use up in your favourite film camera last week? And what about your other film cameras? The reality is that nowadays we don't so much fix cameras, but rather clean them and restore them so that they look good on the shelf.)
On the picture above, the light sensor is clearly visible running from the top of the mirror nearly to the middle. This appears as a fuzzy patch with an amber tint in the viewfinder. (I find it a little bit disturbing.)
This is as far as I got with the disassembly of this camera. I cleaned it, took out a slight dent from the prism housing, installed new light seals and a mirror damping foam and put it back together. Now it looks better.