Great video Mark. Your description of the power switch loop/thermoswitch black AC wire got me to thinking. I might run the fan AC jack black wire to the closest thermoswitch "hot" terminal rather than back to the transformer terminal strip. That way, if the amp overheats and shuts down due to a thermoswitch opening, the fan AC jack still has power, so the fan stays on to help cool the amp. Plus, it's a shorter run for that black AC wire.
Thoughts?