I have spent a couple of hours going through the chassis checking resistors, I have replaced four that were high.
I now have possibly found the problem, there are two black wirewound resistors that check open, but cannot identify them from the circuit diagram.
I am sure these had continuity when I checked through the resistors during recapping the chassis, both look physically fine with no signs of overheating.
One is connected from pin 5 on V5 (D77) to pin 1 on V6 (Z77). This is not on either of the circuits I have.
The other is from pin 5 on V6 to C29. I am using the circuit in post #59.
Mark