I have just bought an unused 1996 Model M 1391406 and was really looking forward to using it, but have been very disappointed to find that hitting the keys - typing, I mean - produces a truncated high ringing sound - like a metal plate being hit, but naving the resultant ring stopped after a moment. Happens when a key is hit. It sounds a little like, though not quite as bad as, the ringing I got with my Cherry G80-3000.
I have not read any report about this issue with the Model Ms - even a late one like mine. All I want is the click and clunk without the high ppitched ring. I assume it's the metal plate inside that's making the noise .
I suppose that's that - back to the Customizer for me - a tiny bit of a ring but not a problem.