Mate of mine gave me an old Ascii-pad he found in a thrift shop. First I thought it was completely broken, but it turns out that out of all buttons, one (the B-button) still works: if you press it, the pad behaves as if all buttons are pressed. (used Windows 7 and a cheap SNES/ USB-converter to pinpoint the problem, but as far as I could see, when I plugged it into my SNES the problem was the same).
Took a look inside, and apart from lots of dirt everything (switches, contacts etc.) it looks ok. Anybody got any idea what might be wrong?