Montage 7 keys not playing at the ends only the middle

I Have a yamaha montage 7 after a power outage the low keys stop playing for the low circuit bourd and about 5 key on the hight end. Any assistance on hiw to deal with . Thanks

Any water damage? Have you checked the boards for any damage?

Service manual is available at Client Challenge

No visible water damage. Meet a few small flying insects died inside .

i would replace all three pcb. probably the middle board is bad

I was able to get new ribbon cables and the one to the left was were all the problem came from .so I replace it and all is well so far. Thanks guys you assistance, it help alot.