[DeckApe]

Found the smoked component. It was the 150-ohm, 1-watt resistor (#60 on the schematic) which is tied to the negative end of the 12mF cap (#61) and a lug where the 15-ohm resistor (#59) ultimately goes to ground on the bakelite block. It still checks out at 152 ohms, but there is some definite discoloration on the body.

Given the center of the rectifier tube lit up dramatically, it's getting some pretty hefty unauthorized voltage somewhere... I will fire it up again tomorrow without the rectifier tube and see what giveth. I'm sure as heck not dropping my spare 84 into the chassis until I figure out what happened.

(Oh, I'll also ohm out the transformer to see if there are any clues. Something I should've done beforehand, perhaps. D'oh!)