Next Step: I went down the board, removing the old brown adhesive, testing each component, keeping the original parts that test good, and replacing the ones that don't. The original electrolytics and all but one of the old ceramic caps needed to go. Also found some earlier replacement resistors that were the wrong value so replaced those, too. Having the redrawn schematic on hand made the process easy. Next step is to remount the circuit board, rewire the tube sockets, and test all the pots and jacks. BEFORE: AFTER: Still need to fix the lead dress on the north side of the board but I'll do that when I redo the grounding and pots in the chassis.