[DaveWM]

looks like some fold over on the left, maybe need the horz setup procedure. ( oops forgot zeniths dont really have a setup procedure other than adj the hold control for good lock, you could try just adj the horz hold of tube swaps below do not help)

Anytime I have issues like this I start with new horz out and damper tube, and horz osc.

also agree with zeno, you have to not drive sets too bright, esp if the CRT is not great on cutoff, or you get the vert retrace.

Test pattern generators are often not the best signal source. Be sure to test them on a known working set to make sure they are not the problem.

on vert size, 1st suspect would be the cathode bypass cap on the vert out (100uf), next I would go a head and replace the .1 1KV boost filter cap on the vert size pot. Any leakage there would drag down the voltage supplied to drive the vert osc. you could confirm this by checking voltages of the plate of the vert multiplier. I routinely change out those since I can't test for leakage at 1kv. Be sure to try a new tube 1st both the vert multivibrator and the vert output. Never assume tubes are ok, and you cant test them as you need to sub those.