weird horizontal issue with quasar wp3931aw

[Hemingray]

Have a quasar wp3931aw 13" (1986) that I got going, (new flyback, etc).

After finally getting it up and going, there was no horizontal lock at all. Found a small 47mfd/35v cap that was blown out the bottom, swapped it. same result. Removed it and tried the set again (to see if that is the issue), and lo and behold, we have horizontal lock and stability!

Put the cap back in (a good replacement), and all lock is lost. fiddling with the hold control does nothing. Remove cap, all is good again. Right now I am running it with the cap out and the picture is rock solid. Is there some difference in the new flyback that's causing my set to run without this cap? (I bought it from electronix)