Rca 21D641 HV issue.

[Eric H]

Just for fun you might try swapping the vertical and horizontal connections at the plug.
Sometimes after market parts are wired differently and if you just copied the connections from the old one it may be wrong.

Easier still, just hook up the horizontal and see if you can get a flat line across the screen (brightness low).

I have hooked up yokes wrong before and the results looked a lot like this, not that it can't be caused by bad caps but it is an odd pattern.

You could also just start recapping the set and see if it gets better, if it hasn't improved after recapping the horizontal then you might revisit the yoke connections.