I inherited an old IBM PS2 keyboard Model M2 (made by Lexmark). Part # 1395300, and manufactured 15-Feb-1994. I have read many guides on how to clean it, and also looked at some of the videos, but all of these seem to deal only with the keys. If I understand it, this uses the buckling spring design, rather than the capacitive circuit used on earlier keyboards.
Once disassembled, connected to the microprocessor board are two clear flexible plastic membrane sheets with circuits etched on them. And below the sheets is a removal piece of silvered reflective plastic. I have found nothing that tells me exactly how these plastic sheets function. Does pressing them together under a key create the character, and if so, how are they kept apart normally? And how are they, and the reflective plastic cleaned?
I ask because a few of the keys do not seem to create a character when pressed, and a few others repeat the character endlessly.
Thanks for any help you can provide.
Harry