Wierd problem that suddenly went away

[Username1]

Penthode is on the right track as far as suspecting parts based on the time it takes for heat to effect them on a tube set. Some of the parts you may be looking at are not candidates for freeze spray. It just don't work all the time. I would bet on a cap breaking down at a certain voltage. Screen grid cap in the vertical output or a cap across the yoke. Since you recapped it its possible you got one with poor voltage ratings, or its just going bad. Parts can go bad new as well as old. It might also be a good idea to look at just how close all the leads are on the parts you put in, a little dust across leads too close can be the trouble. Intermitants can also be tracked by hitting individual parts with a wood dowel. And most frustrating it will take time to track down....