All vintage 35mm cameras were originally equipped with foam seals to create a lightproof encasement for the film. These seals are located around several common light entry points such as the back door hinge and the edges of the door. In addition, a small foam bumper is placed above the retractable mirror on the inside of the camera body to protect the focusing screen. Over time (most cameras requiring such seals are 30 to 40 years old), the original seals can erode and become a gummy mess resulting in light leaks and ruined photographs. With a steady hand, replacing these seals is a simple task.
Prepare your work area. You will be dealing with very small materials so make sure the area is clean, well-lit and free of any excess dirt or dust.
Remove the lens from the front of your camera by depressing the small tab near the mounting threads. Place the camera on its front so the back door is facing up. Open the door by pulling up on the film rewind knob, located on the top left-hand side of the camera.
Wrap a small wad of paper towel around a cuticle tool or toothpick and moisten it with a solvent. This will be your scraper tool that will remove all of the old gummy foam. Locate the grooves where the edges of the back door fit into the camera body when closed. Starting from one side of the camera, insert the scraper into the groove and gently push out the old foam. Scrape the entire length of the groove, adding more solvent as needed. Repeat for the other groove.
Replace the wad of paper towel with a fresh one and re-dampen it with solvent; use a bit more this time so that the wad is saturated. Locate the door hinge. On both or one side of the hinge you'll find patches of eroded foam seals. Touch the wad of paper towel up and down the old foam, allowing the solvent to soak in for 30 seconds. Gently scrape the seals away with your tool. Wipe the area clean with a fresh bit of paper towel dampened with solvent.
Turn the camera over so that it's facing up. Locate the eroded mirror bumper pad (at the edge of the milky-white focusing screen nearest the lens mount). Place a new wad of paper towel, again saturated, on your scraper tool. Using your tweezers gently pull up on one end of the foam bumper, moistening each part of it with solvent as you work. Avoid squirting solvent directly onto the bumper as it could damage the focusing screen. Also, if the bumper foam begins to crumble, tilt the camera so that the pieces do not become lodged inside the body or on the focusing screen.
Clean your work area of debris including old foam particles, used bits of paper towel and any spilt solvent.
Cut your adhesive foam to size using scissors or a sharp hobby knife. If you use a hobby knife for more precise work, use a piece of cardboard as a cutting surface. Door hinge seals are cut from 1mm thick foam, groove seals from 2mm foam and mirror bumper from 3mm foam. As each vintage camera will have different dimensions, use yours to estimate the appropriate seal size; the fit of each seal does not have to be exactly precise.
Open the camera's back door. Push the long thin cuts of foam into the grooves, one strip at a time. Adhesive is not required for groove seals, so you do not have to remove the backing from the strips. Use your scraper tool to push the seal into the groove. Close the door to see that they are secure. Open the door once finished.
Peel the backing from the foam intended for the door hinge seals. Lick the adhesive side of the foam to allow for ease in positioning the seals. Position the foam according to the placement of the old seals. Press firmly on the foam with your fingertips while the adhesive sets.
Turn your camera over so that it is facing up. Peel the backing from the foam intended for the mirror bumper and pick it up with your tweezers. Lick the adhesive and, very carefully, place the bumper into position at the edge of the focusing screen. Gently press the bumper with your fingertips for 30 seconds to allow the adhesive to set.
Clean your work area and replace the lens on the front of your vintage camera.
To ensure that the mirror bumper's adhesive sets correctly, change the camera's shutter speed to bulb mode ("B" on the shutter speed dial at the top of the camera) and hold down the shutter release button for 30 seconds. There are many pre-cut light seal kits available from online retailers. See the link in the "Resources" section for a number of kits and detailed replacement instructions for many vintage cameras.
Never touch the focusing screen with your fingers, scraper tool or anything else. It is a very sensitive part of the camera and can be easily damaged -- typically beyond repair. Changing light seals on a vintage camera is simple enough, but the work requires concentration and patience. To avoid a poor replacement job (and the light leaks that will follow), remain focused and take a break between each step in the installation process.