Damage was described before I bought the camera and I figured that I'd be able to do the repair; tonight, I did. The seller sent knobs and parts as per my request; nothing actually fit or matched, but I got the idea from them. The threaded rod was broken off and the knob was missing. The part controls rear swing and holds the back tight; it is essential.
The entire side was removed. All those screw slots pointed the same way (and now still do). The slider was 78mm long, brass, and had two threaded rods. It was cut. One of the parts that were sent was cut. Two pieces now slide as one. It didn't slide at all before.
It feels good to have it working better now.