ok so I bought a controller that had a 'broken' LB, after testing I found that the LB button wasn't working and that P4 LED was out, everything else worked properly though. So, I disassembled the pad and tested the LB switch itself and that's working properly so I just need to fix the plastic button part of the casing, but I found a bunch of corrosion on the guide button pad and P4 LED. So I cleaned the corrosion off of them (I'm not worrying about the LED right now) and went to test the LED and guide button operation and now the P4 LED still doesn't work (which can probably be fixed by replacing it), but the formerly working guide button doesn't work at all now...
Here are some pics:
Corrosion on pad and LED:
after cleaning the pad:
when I cleaned all the corrosion off it had eaten all the way through to the white of the PCB... the black area is still attached to the main trace below it, but the button is totally unresponsive. any ideas? or is it junk now?
btw it's a CG controller if that makes any difference...