I own this receiver. It still works. I have the original owner's manual, and it has a schematic in the back of the manual. If you need a copy of it, let me know. It would be hard to scan, but I can try to get a good image.
I've got this amp as well, and am trying to figure out a power problem. Fairly sure I'll need to replace the Tx, but will need the schematic to figure it out. Any chance you could scan and email it to me? its witheredfigtree@gmail.com