Here's a waveform from pin 3 of the 6DR7.
I didn't see any vertical foldover when that was taken. The height control was fully CW, giving maximum height.
A while back I measured resistance of the vertical yoke windings from the plug. Sams says each winding should measure 18 ohms and the thermistor 4 ohms cold. I measured 18 ohms between pins 10-11, and 25.2 ohms between pins 9-10 which includes the thermistor. So my thermistor measures 7.2 ohms cold, I guess. No idea what it measures when hot, but at least it doesn't look shorted or open.
I see lugs Y-5 and Y-6 on the Philco schematic. I assume you pull the yoke to get access to them.
Phil Nelson