That camera can be overhauled w/ a straight bladed screwdriver basically. I know, because it's the first camera I ever overhauled, and after a lot of false starts (make sure you mark things and/or take some pics of the focus gear relationship) it took really nice photos. Wish they had strap lugs though. Very simple camera, Just take the knobs off and whatever else is needed to take the top off, and get in there and see what's up w/ your rangefinder. Don't touch any of the mirrors if you can help it. You should be able to see what's wrong. I loved that lens mount! Every time I took the lens off it took me forever to figure out how to get it back on, and getting it off is not exactly intuitive either. Great shutter....wheeeeng!