You've probably been told this before, but replacing seals is incredibly easy. It demands patience rather than skill, I change them on old SLRs as a matter of course.
Originally Posted by Roger Cole
Scrape the old gunk out with something like a cut down cocktail stick, clean the remains with a thinner - it doesn't have to be clinically clean, the new foam will seal the remains in place (I use methylated spirit, but nail varnish remover would do), and work the new seal slowly along from one end, remembering to cut a gap for the frame counter top left. An experienced hand could probably do one in twenty minutes at a push, but put some soothing music on, pour a glass of something nice, and take an hour thinking beautiful thoughts about restoring a camera from the junk pile. Some foam is so perished you can miss the removal stage and lay the new stuff on top. Don't use force at any stage, and you'll wonder why you never did it before.