The power interlock puzzled me for a bit. The pin spacing is wider than usual, and it is polarized even though it is a cold chassis set.
Luckily, it is the same style Zenith used and I had a spare from some recent projects.
Pulled the rectifiers and exercised the power switch a few times to clear it out but nothing. Traced out the wiring and discovered there is a safety interlock in the yoke plug. I bypassed that and viola! Nice to see the tubes light up.
Now, keep in mind I still have the rectifiers out as there is still much work to be done underneath.