Roland KR-370 Right Speaker Muted

Hi all,
We have a Roland KR-370 whose right speaker has stopped making noise altogether.

We have opened it and found that there is no evident water damage or corrosion as well as no blown fuses or anything that looks out of place. All the ribbons are in place and the pins don’t seem broken or bent.
Could this be an amplifier issue? We are thinking perhaps the IC has blown.

Any help or advice would be very much appreciated.