Sure enough the focus rheostat is bad
It has a Dumont poart # and is likely the original. Should be 1250 not 7.8M !
The break is somewhere near the scratch mark..
So with the tap on one side of the break, all the power goes through the 1450 ohm power resistor, on the other side the focus coil which explains why it was sometimes cold and others blazing hot. Either way, the set is being starved of power for the tapped bleeder resistors.
I'll have to track down a replacement. I'll see if I can dig up a couple 680 ohm power resistors in the meantime as a substitute.
Also tested all the tubes and found a bad 6AB4 and 6J6 in the tuner and two bad 6AU6 in the IF.
The set must have been in a heavy smokers home. All that goo protected the chassis nicely.
Also discovered this dangling coil near the tuner. That doesn't look good
