The oscillator adjustment stopped working. It is pretty odd, as I was able to adjust the number of bars (frequency) previously. Now the APC control has no effect.
You are correct that Auto Color Control is for the intensity, not affecting 3.58 mc osc.
Here is the Sams schematic with notes, and I will find my Zenith version copy and mark it as well.
The H-pulse and burst waveforms to the sub carrier regen look good on the scope. I am thinking the IC took a crap here, 221-42 or ECG 714. I will see if I can get a new one.
Zenith 25DC56.pdf