I’ve traced the power supply schematic past the SCR and out to the power transistors that are attached to the big heat sink. This part of the schematic might be a little questionable because a lot of the wires are covered up or obscured by other components and a little harder to follow.
The schematic so far:
I’m up to the control board now. It’s small, but has a lot of wires coming in and out of it. Fortuantely it’s all point to point wiring on perfboard, so I don’t have to follow any PCB traces.