Dumont RA-110 from ETF

[wiseguy]

did you replace all of the paper caps yet?
there are a few in the Horiz Sweep area that when bad/leaking will cause this, and also a weak damper tube 5v4 would cause this, if the Horiz drive is turned up too high will cause this also
I would start first making sure all the caps in the Horiz osc/output/flyback are new, there is a resistor r122 and r120 that will change value, check those
But the Capacitors c101,102,103,106,105,107 is very important