Zenith 25EC58 poor focus

[Electronic M]

I'd replace those white caps for sure.

It's possible your screens may be set too high. I'd turn brightness to minimum, flip the service switch, turn all 3 screens down till the line vanishes, turn red up for a just visible line, turn green up for yellow then turn blue up for white, then put service back to normal and adjust brightness for pleasing picture and if necessary adjust color drives for good grayscale.

I have a Setchel Carlson monitor that had a focus issue that drove me nuts till I realized some previous yutz maxed out the screens on a good tube.... turning them down instantly got me good focus.