Peavey VTM 120 Repair Troubles

[The Dude]

IMO, it's highly unlikely that a failing PT would cause tubes to red plate, unless you were losing the bias winding. Your tests proved otherwise.

[g1]

Maybe they meant the OT? That would make more sense.

[DrGonz78]

Any repair shop that immediately jumps to power transformer as the first on the list of suspects with symptoms mentioned in this thread would make me weary.

[Baronkarza]

I doubt the PT is bad.

Intermittent faults are the most tedious.

Let's eliminate the obvious.

Check for cold or bad solder. Are ok ?
Check molex connectors, (if you left any) Check resistors, cap, diode, sockets. Are ok ? Pull those. Are firmly soldered ?
Check the components around the output tubes ( Screen resistors, diode zener) Are ok ? ( maybe change 100R with 470R-1k can help ? )
Check voltages. Without and with output tubes. Are ok ? ( Plate, cathode, screen, negative voltages, B+)
I read, you have changed the place the output tubes, for excluding them from equation. Check again.

[Helmholtz]

Absolutely no indication of a PT problem so far.

[Jynk_O]

Update: got the amp off of the bench, a couple good techs have had their try to no avail. Said they couldn't find anything that they could deem to be the cause, besides a suspiciously uneven output transformer.

A huge bummer, especially after all the work put in to just get it to the starting line. Will bring to one more tech, whose got a few decades over others and has been referred by peavey since this amp came out.