[morzh]

Arran

I thought you suggested the smoking occurs due to the field coil being disconnected.

If it is connected, anything can be the reason, and I thought of RF 78 tube shorts.
Part #19 short (if the field coil IS connected) would require also some short in the Det. oscillator tube, but even this will not reault in #7 smoking as it is serialized with some 50Kohms resistance and the drop on it (again, if #19 is at fault) would be so small (0.5% of the total voltage), it is far from causing anything like 200 Ohms resistor (also probably 1/2W) to smoke.

If #61/62 do smoke, this indeed may be (potentially) due to the field coil missing; #7 - unlikely.

I would say, if #7 smokes with the field coil removed, it will smoke with the coil in place too.
I would look for shorts in wiring - the schematic does not show any path that can do it.