I will assume it uses a 9-160 HV module. Its the big one at the bottom with the
HV transformer.
Looking in the back on the right rear under the focus control there is a cap, 10mfd 315 V IIRC. Change it. Will cause your problem & others.
If you have to remove the board its easy when you learn the secret.
Let us know
Dont rejuve for now. Thats last resort & using clean & balance is better
& less risk.
73 Zeno
LFOD !