Pulling the logic board and replacing caps should not affect your screen focus at all. I should know since I have yanked out my motherboard and put it back in dozens of times without disturbing the screen at all.

And although it could be a bad component as trag said, it could also be that someone bumped something they shouldn't have when the logic board was replaced. Therefore, everything needs to be carefully checked. All connections from the analog board to the CRT yoke need to be examined. I just can't imagine that a resistor would suddenly go bad after the logic board was pulled for a cap replacement. It is far to coincidental. No, something must have been bumped and either yanked out of place or broken to get your screen to flake out like that all-of-the-sudden.