[Jamie]

   

Update -
I replaced the 80 tube with a known good one, and rerouted the wire that provides plate voltage. I plugged the radio into the variac, and slowly added voltage while holding on to the electrolytic capacitor. By the time I was up to 55 volts, the capacitor was too hot to touch. I cut off the power. The overheating cap has the negative lead running to resistor 47, and the positive connected to the filament of the rectifier tube, and another wire leads to the speaker. This is how the previous cap was wired. I simply swapped in a new one.

The only other thing that looks suspect is a micamold cap (see photo) that runs from the ground lug on bakelite block no. 7, to the bandswitch. Don't know if this could cause the issue, but I figured it was worth mentioning.

So, I'm stumped.
Question is, would a total recap and resistor replacement possibly cure this problem? Or do you think is this something that is only caused by a wiring error or a possible (hard to find) short?