Mamiya M645 1000s Film Camera Body Only Not Working

It comes with Focusing screen, 220 Insert

Cosmetic Condition: 7/10
It shows signs of use.

Mechanics: Needs repairs.
The camera appears to be stuck in multi-exposure mode. The multi-exposure switch appears to be damaged. Film advance lever moves, shutter cocks and fires, but the film loaded in the insert does not advance.