So I have a similar problem as described in THIS THREAD (www.ultimate-guitar.com/forum/showthread.php?t=1281083) but it descended into flaming so I didn't post there. The amp turns on, but I get no sound and the tube filaments don't glow.

BUT, I can add a few more details:
  • It stopped working after tumbling around in my trunk for a week
  • Yes, the power light turns on
  • Yes, I checked the fuse
  • I also put in new tubes
  • I installed a standby switch which could be a culprit and if I knew how to remove it and test, I would.
  • I measured with a multimeter and power is getting to the big transformer

I have a fair amount of technical aptitude and sorta know my way around a circuit board. Sorta (I have built but not designed guitar pedals from scratch). If anyone can tell me where to measure currents to check for example, the transformers, I could do that.
Found the solution on another forum: I opened the plastic tubes containing fuses that were on wires coming out of the power transformer and sanded the contacts.