I managed to unscrew the rewinder while removing a roll of film and while doing so out popped a washer and another washer like piece which had a 'lug' coming out of the side. They appear to sit on top of a spring but to be honest I can't figure out which order or how exactly.
I've since just screwed back on the rewinder handle bit.
I've searched online for perhaps a diagram of the rewinder in the hope of working out how to replace the parts.
