Part 4: First Response
The response from Bruce (opposite) was helpful and informative, although his description of where the reverb driver tube should be ("near the output transformer") was a bit ambiguous - near the speaker output transformer or the reverb output/send transformer?
By much trial and error I later figured it should be the latter.
Over the next few days I did my best to check Bruce's points as well as I could and then emailed him again - see part 5.