[Ron Ramirez]

Take a good look at your 24 and 27 tubes, especially if they are the old globe shaped tubes. Watch them while the set is in operation, preferably with the chassis and speaker out of the cabinet and in a room with the lights dimmed.

Watch and see if any of the tube filaments flicker or go out in one of the 24 or 27 tubes. If so, that's your culprit.

I've seen this happen before in the older Philco sets. If you find one with an intermittent filament, you could try pulling the tube and reflowing the solder in the filament pins, but more likely than not, it is a defect in the filament structure. I've seen these tubes with filaments that would flicker pretty badly.

The newer (ST, taper-top or shouldered type) 24 and 27 tubes do not seem to have this problem.