Thanks Richard. Yes I checked all the obvious stuff first...RF gain control,
persnickety "RCV/TRCV" slide switch on the side, antenna bulb fuse etc. Also
removed and checked the trimmer and coils of the IFs. I'm now focused on
a -0.25 VDC bias measurement on the 2 IF tubes instead of the -0.10 VDC
shown on the voltage chart.

Will update as progress is made.