[DuMont]

        I had finished a complete recap of a Philco 46-480, as well as replacing original 1/4 watt resistors with 2 watt flameproofs where needed,
and a new loctal socket installed for broken one on the 7F8 converter and hand-cut a new insulator for one of the two electrolytic cans. (The original insulator, naturally, did not match the Richey Gold can I used as a replacement) 
Connected the chassis to the speaker, turned volume and tone off, and then a slow power up through the variac connected to the isolation transformer, and when I reached 117 VAC on the variac, everything seemed to be holding together, but the output tubes and the transformer were both running hot.
I rechecked everything, paying particular attention to making sure I had put in the correct resistors, then tried again with the same result.  Got the Fluke meter out and checked the B+, which should have been 195 DC according to Philco with a 117 VAC input.  It was up around 280 or so.
Checked everything AGAIN.   My house current from the wall receptacle is 120 VAC, then it goes through the isolation transformer, then to the variac - and then - WAIT A MINUTE.  The Variac?   I unplugged the Philco and plugged in my Fluke.  Where the variac dial and meter was reading 120, it was actually putting out over 130.  When I turned the dial down to about 96, it read an output of 117.   I left the dial there and plugged the Philco back in.  Bingo.  The voltage readings were spot on.
SO:  It may not always be some esoteric answer, but rather something as simple (and annoying) as a variac that's out of whack.
Sigh. 
DuMont