[RodB]

Hi Richard. I think the way this one works is that when the tube starts conducting the oscillator primary gets a pulse from the plate circuit which starts the secondary oscillating. This in turn will induce a signal in the secondary of the cathode circuit. This local oscillator signal will then mix with the grid input signal to produce the IF. The oscillator continues to oscillate from capacitor 12 in the plate circuit. Maybe if you haven't changed cap 12 you might try replacing it.