I got myself a Super Famicom and two controllers from Japan but on both controllers one of the buttons didn’t work. This isn’t exactly surprising given that they are about 25 years old, its pretty normal. So I decided to crack then open and clean them both up. Here is one controller on which the “start” button didn’t work.
This is the internals, I have disconnected the lead on the other side. So basically, those black dots on the top item correspond to a buttom and they are a little bit conductive, so that when you press a button, it hits the circuit board as you can see in on the lower item.
Lets look at the circuit board closer.
The white line seems to be the contact point and the start button is pretty dirty. The other buttons are ok but need a clean anyway.
I live in Estonia and I use stuff called “piiritus” which is your standard rubbing ethanol. I put a little onto a cotton swab and that crap comes right off.
Yeah! I cleaned that bastard on up good! Now the controller works great again!