Someone had installed a solid-state rectifier in this amp and converted the circuit into something like a 5F2a Princeton with a 6SL7 preamp.
The amp came in because it had let some smoke out, but the problem turned out to just be a short in the (likely old surplus) capacitor can. I replaced the cap can, cleaned up some of the wiring, and modified the output stage to compensate for the increased B+ voltage due to the SS rectifier and 120V+ volt mains.