The rangefinder prism has separated.
I've fixed 2 or 3 of these.
The old balsam had become brittle and the jolt was enough to knock it off.
The old prism needs to be pushed out, and the glue cleaned off, without damaging the reflective coating. Then reglued.
It is very straight-forward.
Condolences, on your unfortunate accident.
Vick