Heyo

I hope I am in the right subredit for this kind of question. I have a c64 and bought a really beutifull controller for it on a fleamarket. It looks like its a bit broken and I would love to fix it.

Its a Sigma 1001 controller (see picture). I tested the pins on the plug with a multimeter, and I figured out that the directions seem to fire well except the left switch but there the micro switch itself seems to be broken.

The two buttons dont fire at all. I tried reconnecting the yellow cable to the spot circled in the picture becasue I think its a grounding cable which came loose. The cable was only connected to the main board and didnt connect anywhere when I first tested it. This didnt fix the issue and the puttons still dont trigger. I tested the switches themselves fir the buttons and those seem to work fine.

My question is, is there something obvius based on this info that I could do to fix the controller? I am also planning on buying new microswitches to replace the old ones and I am not sure what kinds to get. I would love to use this controller with my C64, zx spectrum and atari 2600.

Thanks for the help!