See the big diode next to the yellow Switch mode PS Transformer?
put red probe on the band side of diode measure the dc
You need a good ground, most of the time the H.O.T heatsink is a cold ground.
Need to turn back the trim pot in PS circuit to where it was.
And a cross hatch pattern is best to to adjust image parameters, then adjust to game image.
Check the b+ means what is it now and after you turn the pot counter clockwise
just say the voltages you measure
as a reference point and see if image changes enough.
to where the white out matches up on the pot.
you got the original yoke and tube for this chassis and using it now?