[Heatercathodeshort]

I have a spare copy of the VC4 manual if you would like it. PM with full name and address please. It has an actual size chassis layout and a huge circuit.

The added resistor is probably the 7 ohm HT surge limiter to the silicon HT rectifier.
Take care as the mains dropper is in two section, heater dropper and HT smoothing so take care with tests.

You don't even need a meter to check this one. A 15w pygmy bulb on two leads, one connected to chassis will give a visual indication of what has gone open circuit. Likely a section of the mains dropper or the heater of the boost diode PY800/801 pins 4/5.

Come on boy this is an easy one! Results by the weekend?

Probably the best monochrome chassis ever produced.

Regards, John.