Cvp-98 work on one channel only

Hi, my clavinova cvp-98 does produce sound only on right loud speakers, treble, bass and also headphone. Lest side is silent.
The amplifier board shows no sign of damage ( capacitors are looking ok) and I removed and cleaned all board connections.

Is it correct to suspect that the main board is defective ? And how can I make sure?
I may have the opportunity to cannibalise a cvp-96: are the main boards compatible? ( and would I loose the bass booster wich seems to be a feature specific to the 98 version?)

If the main board, welcoming a solution to find one.
Thank you!