[jerryhawthorne]

Perhaps time to go again back to basics, which I believe in. Turn it on and do the good old center tap touch of the volume control with it turned up. wait until such time as the volume drops, then do the good old touch on the center tap of the volume control again. Is it as loud as when the voltage was high? Is the power transformer hot to the touch? If it as loud as when the set was cold, and the transformer is not hot, I don't believe the problem is related to the transformer and the observed voltage drop at what I am guessing is the first cap before your new resistor added for the field coil. Would be interesting to then going through the whole procedure of cold start, measuring after the new resistor combo for the field coil and see what the voltage drop is. I suspect it may be much greater than before IF the problem exists further down the line. The starting cold voltage should be lower than your previous measurements, just want to see what happens when the radio is warmed up and any change. It will start lower than your initial voltage reading due to the resistors, fine it should, want to hear what it goes to when your radio volume drops.
Remember, I'm no expert!