So, after re-checking all the caps for shorts, and then removing the chips to no avail, I moved on to testing every diode and may have found the problem.
CR948 (Tek 152-0333-00) and CR949 (1N4152) were (and still are) shorted out.
With these two lifted from the circuit we no longer have the low 4¦¸ reading between the +65 and +5v rails, so fingers crossed it is only these two.
For sure I don't have a 152-0333-00 (1N4610) here, although I do have various diodes here, if anyone has a suggestion as to a temporary replacement, in order to test the scope?
James
James55