I opened the back of my rz67 on a shoot and a part fell out. Maybe someone can identify it, since i know nothing about the parts of a rz67..
The question is will it affect my pictures somehow?
Well, experience taught me that cameras typically do not have a single part as surplus, thus any part has a function. Whether this part's function directly affects image quality still remains to be answered.
To me it looks like a roller guide of some kind.
See the bottom photo on page 8 of the manual. It’s the film-tension roller that mounts to the end of the stainless-steel formed flat spring in the film back. This can be seen on the left side at about center height. It bears against the backing paper of the supply spool. There is an identical tensioner for the take-up spool on the right.
I presume that it’s job is to provide some turning resistance to the spool for proper film feeding. It shouldn’t affect your photos, but it would be good to install it if possible. The spring is held into the back with two small cross-slot screws (JIS standard). The third screw (shoulder screw) is a spring-tension adjustment, I believe.
Such film guiding rollers were my firsrt thought, but I overlooked them at first glance at the parts list as they are still mounted and not depicted loose...