Occassionally I have PTK195 lightbox come in with coolant slop on the
front most PCB where vertical circuit & micro are. Usually a wash and
check of components fixes these after several rounds.

Except this one is resisting me. BTW this particular is P56830xxyyy

Every components are checked, cleaned if required and replaced: diode,
caps, and 8 pin SIP reistor pack and vertical IC.

Every time the vertical is turned on or replaced, The 26V side
vertical amp stage dies slowly in several seconds but the ground side
of vertical amp stage is working, giving noisy 3" band of raster in
middle. No overheating or blowing craters.

RCA uses TDA8172 IC between 26V supply and ground with 15V feeding
through IC's output via vertical yoke winding. Voltages are there and
15V starts good then unloads to around floating 22V as deflection
slowly collapses. So waveforms looks like a flat waveform with small
pips for retrace and a ramp sloping down from 15V mid-point to ground.

BTW, 26V is there at vertical IC, no noise either.

Cheers, Wizard