PM'd you.
That 560K does seem kinda high for plate resistor. The schematic I have is for a Zenith J2027, which has a different HOT but uses a 6SN7 that employs triode on pins 4,5 &6 as a Hartley osc and pins 1,2 &3 triode driving the HOT. It receives a B+ of 310V through a plate resistor of 150K. The plate op voltage is 50. There is a little difference, so seeing your schematic will be helpful. Lowering the value of the plate resistor may bring your gain down, but will also help with loading issues involving the network at the HOT control grid. This may bring things to where they belong, restoring your HT. That yours calls for a 560K is a head scratcher.
