Merv,
My 1772 would start up intermittently. I can't remember the precise details but I did a search on this forum and others and read that the griplets joining top and bottom of the psu PCB, after time, could fail to conduct. A good dose of solder applied with my Weller seems to have done the trick. It's a fairly simple thing to try - the psu does get quite hot I recall, and you never know, it may be the cause of your problems indirectly.
The thread here discusses:
https://www.vintage-radio.net/forum/...ad.php?t=69206
Ian