Could any kind soul please tell me how the thin copper-coloured ring (RHS) aligns with the bezel on the Pentax MX lens-mount, please? I reckon it could go one of three ways and I also reckon the tab is to do with the fitment of an M42 adaptor.
Which is how I came to be in this position in the first place... I got an Asahi Pentax M42 - K-Bayonet adaptor which went in OK, but wouldn't come out, despite pulling the catch back as far as I could with my thumbnail (and carefully, a jewellers' screwdriver).. I removed the bezel to see what the problem was, and, of course, the thin copper ring fell out before I had a chance to see which way round it went!