The lens cam follower in the camera in the Leica and clones is a little wheel that rotates when you focus a lens so the wear over decades of hard pro use is imperceptible unless the wheel jams.

Only the Russians did not copy the rolling wheel.

The chrome plating on the cameras registration datum only sees a few degrees of contact as you tighten the lens. On a strip the technican needs to shim the datum to the registration distance as he rebuilds.

The long base rfdr are good for f/0.95 lenses the short base Canon VI ok for /1.2...