"It's only reasonable to assume he wants to tweak because he's out of adjustment. "

No, this is an elcheapo and there is no adjustment for H width at all. There is not even a pincushion circuit. If it was a matter of adjustment there would be no discussion.

"ut you're not understanding something. If you decrease the voltages out of the LOPTF by eg 10%, ie both scan voltage & EHT, the scan size remains exactly the same. Think about why. "

That is simply not true on this type of unit. I have seen it 100s if times. When the regulator, which is a pass transistor, not switching, goes open the set runs on a ballast resistor that is there to decrease dissipation in the regulator transistor. In those cases the H width is small and the vertical has a distortion somewhat like a foldover at the top because it is not getting enough of a retrace boost. That is what that cap and diode do on the vertical IC. The supply is scan derived so it is also low when the main B+ is low.

I understand your reasoning, but in practice that is not how it is, the picture shrink when the B+ drops. I can prove it, want pics ? (have to borrow a camera, lost it)