ISO Yamaha Electone Organ Schematic

[rufustf]

I know the main topic of this forum is stompboxes but I thought someone here might know where I could find the sch. to a Yamaha YC-10 Electone organ. They don't make it anymore and the company has not been helpful. No luck even with a lot of keyboard repair people. Anyone have a tip for finding this old schematic? (The idea is to re-route the bass keys to a separate output.)
Thanks for any help.
Jason Myers