Hello David,
It's getting late over here now, so others may correct me - but I have read over your voltage measurements and it seems that Jimmy has hit the nail right on the head.
Q872 e = +0.7v
c = + 64.6v
b = +1.3v
--> So the V BE should turn it on, but the V CE readings show that it does not.
Checking the parts list is easy. Sphere shows here that Q872 is a 2N3923, TO39 NPN transistor.
If you find any other 150V rated, mid-beta NPN transistor, I would try that to replace Q872...
Good Luck when searching your drawers for existing replacements.
Cheers,
Magnus
