eBay

Mamiya M645 Prism Viewfinder - for M645/M645 1000s etc.

The viewfinder works on the camera, however it is has a known fault which is extremely common on these.

This finder shows the common prism desilvering typical for the M645 system. This appears as a horizontal line/mark in the viewfinder caused by the internal foam aging over time.

This is a viewing-only cosmetic issue. Because the prism is not in the light path of the film, this has zero impact on your final images. It is a well-known quirk of these vintage finders

It may be possible to disassemble the finder and remove the prism, and scrape away the damaged silvering and gunk, clean it with acetone, and then apply "Mirror Effect" spray paint (like Rust-Oleum) or a silver leaf. I haven't had the time/patience to venture into such a project.

I have multiple Mamiya/Bronica cameras/accessories that I will list in the coming days of various conditions so check out listings if interested.