[Tom9589]

Old TV Nut wins the cigar. I had attempted to clean the height pot early on. It is a 3 Meg CTS 201 consumer grade pot. I jury-rigged a 1 Meg pot of the same brand with suitable resistors on both sides to achieve a total of about 3 Meg. That cured the vertical instability! I then took out the original 3 Meg pot and got a better angle at shooting DeoxIT on the resistance element. I put it back in and lo and behold, the problem was cured. I thought about replacing the pot, but it seems that no one carries a small screwdriver adjust consumer grade pot. Mouser was the only one to carry any 3 Meg pots and they were in the $12-$20 range. Drop down to 2.5 Meg and you can get the pots for under $1. There must be something difficult about making a high resistance, low cost pot.

KF4RCA, I had checked the derived sync pules early on and found them very stable. BTW, the signal to the integrator comes off of the HV winding on the power transformer, not the filament winding. It is labeled "HVAC" on the schematic.