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So as it turns out the 150 ohm blue pot was open in a couple spots. I found a 400 ohm pot in a junk zenith chassis and installed it. Convergence isn't perfect with the wrong value pot but it will do for now (see image). With the 150 ohm pot the right side of the picture looked a whole lot better.
Then I tried some tests to check the smearing. It's worst on blue, so I measured voltages on the collectors of the video output transistors. They are way low, blue was only 100 volts and red and green around 125. The collector load resistors quite charred. When I swapped the connections between colours the smearing changed colour to whichever gun was connected to the blue transistor. (Yes!)
I think the collector load resistors are way high in value, not sure what's the root cause of looking burned though. Thank goodness it isn't the tube! Will pick up some parts and keep digging!
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