Some initial readings for the Valve pin voltages: -
All values seem to be on the low side even though the Rectifier is chucking out a healthy 184V D.C. As Mike (crackle) advised in Post #23 above
"If you have not yet changed all the hunts capacitors then voltages will be down all over the radio due to excessive current being drawn on the HT."
Clearly something not quite right with the 12AT7 (V1) at the FM stage - but we'll tackle that in due course.
So several Hunts Mouldseals to replace and some cathode resistors to check.
I'll probably replace that big electrolytic as well C37, 2μF