Yamaha KX88 key contact repair

I have overhauled my Yamaha KX76 and it is all working. I also have a KX88 which I have overhauled BUT the upper 48 key contact has an issue. ALL the “B” keys do not respond. I replaced the lower key contact, but have not been able to acquire the upper 48 one. Any suggestions on what might be the issue or about ordering the part? Just in case the codes on the pcb are LE00030 Yamaha 6 ELNA.M1 94HB 88H

This sounds like an issue with either a broken trace on the upper contact board, or a faulty ribbon cable (or faulty connection) to that board. Neither is a terribly difficult repair, but you will need to spend some quality time with a continuity tester to find out where the break is.

Thanks, my mind was on that track. Not being any type of an electrician or service person and merely a musician that has cracked open computers and synths since mid 80’s this may take me a while. I do appreciate your direction, :wink: