Came onto this late:
I have also restored a few dozen Quad IIs over decades - yes, the power transformer runs hot. Some heat is also transferred from the closeness of the KT66s - Dr. Walker almost made the unit too small! In this sense using the smaller GZ34 as rectifier helps (also runs cooler than GZ32.)
[Technically this amplifier was somewhat ahead of its time, further prestigious in that it was designed during WW2 with the resulting lack of quality materials at the time. Perhaps I may quote the opening statement of the circuit description: "The Quad II main amplifier differs from contemporary practice both in the output stage and the penultimate stage contributing materially both to performance and efficiency in a manner that will delight the engineer."] Indeed!
One aspect to be attended to is the closeness of the mains voltage selector to its mounting screws. Flash-over often occurred with the least amount of dirt on the inside screw (sharp points there!) and placement needs to be attended to. Further, the loudspeaker banana sockets could form an oxide layer over time which would influence contact with the plugs. (Many people replaced these with screw terminals.)
