An admission of failure.

[boater sam]

Have you checked R1 & R2? Is C7a OK?
Unlikely to be the caps in the cans. What is the screen volts off R3?

All resistors are OK.
C7a was broken, 4.7pf neg coef. so is not there. Should have no effect other than shifting the frequency a tiny amount, its to compensate for the tuning cap warming up.

Thanks for the ideas Trevor, see if you can come up with any more please. Tried all that I can think of.

Sam.