M-Audio Prokeys 88 everything works but the Jazz Ride


I’ve been restoring a Prokeys 88 and everything works except the Jazz Ride button. I replaced the blown LEDs and both pots as the treble was loose and made led screen go wonky when you turned it. Those all work fine. Nothing I do though, will make that Jazz Ride sound appear when I click it while also playing one of the last two normal sounds. It’s supposed to layer on top of them. The LED lights up, so that part of the circuit is fine. I’m not even sure how to trace something like this and I may just give up and just leave it be but I figured I’d ask here in case anyone has ever come across this issue.