Well shit, I guess that's another wasted CRT. There are nearly 300 options in the service menu, yet not one of them seems to have an effect on horizontal linearity. There is a vertical linearity option, but that doesn't seem to help fix my problem.
I guess I am being obsessive about the issue, but it's just so annoying that every CRT I've bought since I moved had this same issue. I can easily tolerate a few minor geometry problems, but this one is just so irritating. I was trying to play Donkey Kong Country earlier today and since the ground is wavy and not straight like Super Mario Bros, it looked more horrendous than usual. (The TV, not the game)
Thanks for the help everyone. I guess I'll have to hope I can someday find a decent professional monitor locally, and pray that it doesn't have this issue as well.