Faulty Bulb causing filament problems?

[Cygnus X1]

I have built two SEL guitar amps...one with a 6V6, another with a 6SN7GTA.

I had some strange problems with the second amp. It ate preamp tubes!
Then it burned up a resistor on one preamp tube cathode. Then a resistor started to burn on the B+ to the output transformer.

I double checked the bias on the 6SN7...no problem, running a little cold (67% dissipation by the calculations).

Then, I noticed that the pilot light was flickering!
Just a little, it may have been doing this all along. It flickered even when on standby. Is there any possibility that a bad bulb was interrupting the filaments? Causing these other issues?

It seems to be working fine now...after changing the bulb.

[Bob-I]

If there's any one thing I've learned about troubleshooting it's that anything is possible.

I'd bet that the bulb was dragging the filament voltage down. Low filament voltage can kill tubes.