Dynamic convergence

[MRX37]

I've mentioned this before, but I have a 27" Zenith TV that has rather poor convergence in the corners. No amount of playing with the yoke or CRT neck rings will fix it. The CRT isn't shot yet. It's still nice and bright and has good color.

I'm wondering... the CRT has a fairly small yoke for a 27" TV. I'm wondering if a bigger yoke would improve things? I've already tried repositioning the existing yoke a dozen times.