[Arran]

I pulled the transformer from the chassis and opened the clamshell, removing both halves and carefully sliding the wires from the hole. I checked it again under power (without a load), and there is definitely leakage between the primary and secondary against the core. From the secondary to the core was around 25 volts! But I have since located a 116 chassis for parts, and the transformer tested good. So just waiting for it to arrive. I can probably get the missing driver transformer from it too

 It sounds like it was a mixed blessing in a way, by finding out that the power transformer being shot you had to look for a parts chassis and may have found a replacement for the driver as well. With regard to the driver transformer on the 116 parts chassis is the setup for the power output stage the same as the 16B with the triode connected #42s? The power transformer should not be a problem, even if it's from a 116X, but I don't know about the driver transformer as the console version uses 6A3 tubes.
Regards
Arran