I recently bought a Mamiya 645 Super second hand from a private seller. Overall I'm delighted with it BUT I have one problem: when using the AE Prism Finder N, the shutter intermittently fails to fire. This happens whether the shutter speed is set to AE or set manually (in fact, not sure that it's recognizing the AE shutter speed at all). If you remove the prism finder or use the WLF, the shutter fires fine. Any ideas? Does it just need a service or is the prism finder broken?
Greatly appreciate any help, Andrew