It's finally time for the first power up!
First signs of life

I'm able to tune around the dial and pick up a few stations but only weakly. Also, the volume control has no effect. Neither does moving around the antenna.
Further investigation revealed that pulling out the 1st #26 tube also had no effect. So clearly no signal is coming through from the antenna.
Hopefully, I just made a wiring error on that tube socket or RF coil.