rangefinder parts interchangeable?

[Jerevan]

Are the prisms/other parts in the IIIb, IIIc and IIIf interchangeable?

Just poking around a bit for some options - the RF patch is almost not there and it looks dirty/cloudy when I look at the camera from the front. The viewfinder window is clear and nice though.

How do I find out if it is the mirror or the prism that needs to be changed, without opening the camera?

 

[Particular]

Most IIIc and IIIf parts are interchangeable. A dim rangefinder is aside from cleaning usually due to a bad mirror. eBay seller nobbysparrow sells replacement mirrors. They are fairly easy to replace yourself.

 

[Jerevan]

Thanks - I'll have a lookaround and see if I can nurse the old one back to a second life. 🙂