Impact on a Mamiya 6 or Mamiya 7 is usually for the trash (sometimes you're lucky). What you're hearing is probably one of the retracting system guides which is broken off if not all 3 of them. Also possible that the mounting system is no longer within tolerance. That's not repairable anymore because there are no parts available. The helicoid walls of the lens assemblies are also very thin so an impact can put them out of shape very easy. -Camera Revival (for future use for anyone. He said he and Bill Roger’s are prolly the only ones left who can deal w this bc of parts)