1963 silvertone roundie

[DaveWM]

you may have wired the focus coil incorrectly. its a coil that shifts phase as you adjust the slug. as the phase shift voltage is added or or subtracted from the primary focus coil. think of it like a variable bucking transformer. You should start by puting the HV prob on the focus output and see if you are getting around 4-5kv and that it varies with the adjustment.