I just bought a 500C/M that has clearly seen some miles, but seems to be in good shape overall.
However, I've noticed that whenever the shutter is released, the lens shifts back a little in the mount. More specifically, it feels like it pitches down at the bottom of the mount, where the cocking and release couplings are. It's much more noticeable with heavy lenses like the Distagon 50, but it's there even with the Planar 80.
The lens is for sure mated properly and locked in. It doesn't sit cockeyed in the mount, the catch locks with a decisive click and the release button pops out smartly, the index sits at the 12 o'clock position (right between the E and the L in the nameplate), and there's no more than half a degree of rotational play.
As this is my first Hassy, I don't know if this is normal, bad but tolerable, or a sign of a serious problem, and whether it's fixable. I've been led to believe the Hasselblad V cameras were designed specifically to be maintained and repaired for a long service life, so I imagine it is repairable, it's just a question of how involved and how much it will cost.