Hi!
So I bought a new film back on ebay for my SL66 which claimed it was working fine. Upon mounting it for a few test cycles, I found the film advance gear (the one that connects to the camera) completely locked up. After some fiddling, though I can't quite remember what I did, it became unlocked although only partially. Basically, when I fire the shutter, the initial crank turn will only make it a few degrees before locking, so it seems to me there's some mechanical function of the back preventing me from advancing the film.
However, if I pull the double exposure lever on the crank and release it after the initial clockwise motion, the crank winds back into the ready position just fine. As far as I'm aware, this cannot happen unless the film advance gear turns in the opposite direction though without affecting the film advance. Basically this leads me to believe there is some gear in the film back between that gear and the initial film loading crank (which works fine) preventing film advance.
Is there an easy fix to this? I've tried everything I can think of because above all I just want a working film back, rather than having to send it back to the seller and buy a new one. He said it worked when he tried it and it doesn't feel like it's a mechanical fault, more that some natural mechanical function of the back has locked it up.
Thanks in advance!