My n64's translucent green controllers z button doesn't work, so thinking it was the membrane i swapped it out with a different grey controllers whos z button worked. And it worked for a few button presses, then stopped working. Then started again and then completely stopped working. So i'm confused is it the membrane or the actual little z button pcb? For that matter could it also be that theirs dust or something gumming up the controller port? Or should i just scavenge the parts and buy a new controller? Any advice is appreciated.
Did you clean off the membrane's contact pad, as well as the contact for Z on the pcb? If there is junk on them, it's just as possible there is a bridge built up on the pad and Z is hung pressed. Could also have too much resistance to work through the junk layer if it is built up decent.
I'd start there.
I'll try that time to bust out the isopropyl 90%