Two '77 Fender Twin issues

[Minty]

Okay so the hum right now is mostly under control! I think half of it was my single coil pickup being too close to the head itself. Ooops! This head has an issue with the reverb...when the knob reaches around 7 or 8, a loud unbearable high-pitched tone...I've swapped the two 12AT7's around to see if it made a difference, but it didn't. EDIT: Fixed the reverb. I think cleaning all the RCA contacts thoroughly helped as they had become slightly corroded.

Also the tremolo works on neither head. I've plugged a grounded RCA cable into the pedal socket but no still nothing. What should I be looking at next...the bug?

[Enzo]

You should be looking at the circuit, not the parts. Is the oscillator oscillating? If so, is that reaching teh bug? Does it flash? If there is no oscillation, all the bugs in the world won;t help.