You know I don't ever think I've seen a truly dead IBM Model M Controller. Most of the time it's due to liquid spills on the membrane or PS/2 compatibility issues. See the PS/2 Compatibility Wiki to make sure your computer(s) is not on the list.
Tried on gigabyte boards, Dell boards, Asrock boards, Asus boards, my Toshiba A300 satellite laptop with a converter (actually 2, to ps2 and to usb xD which works perfect with my cherry g80), and no matter the computer it did the same, but at first it was working very well, just as a brand new. AH!And also on an old 386 olivetti computer, and the same.
Also, when I cleaned it I found food inside, you know, it was on a school, the kids might used to eat and drink on it...
But anyway, thank you both and I will fix it when I have time, Im getting another one in proper condition!