Good news!
The radio fired right up and plays well although the dial scale is a bit off.
I was puzzled by the lack of HV though. A scope revealed no drive signal on the HOT grid.
After more time than I care to admit, I realized that when in radio mode, the TV sweep circuits are disabled.
Now a fluorescent tube glows brightly when placed near the flyback
I had to splice in a conventional anode cap as the original is the goofy snap cap Dumont used.
Woohoo! We have a raster on a little 8XP4 bench CRT!
Recapping continues...