Bad geometry can either be caused by the power supply or by the little magnets on the neck of the CRT. Since those magnets are a pain to work with, I'd suggest a power supply repair or replacement first.

I verified this by using the same CRT with two power supplies (on an SE). The image was smashed on one side and not the other (if you had two circles in MacDraw, the one on the left would look more like an ellipse) when using the first power supply. The second power supply, pulled from a Mac known to have good geometry, fixed it without any adjustment to the CRT.

Of course, magnetic problems are always bound to occur on CRTs and often get worse with age (from my experiences). Even new CRTs are like this--I have a Sony TV that has a similar problem (the entire picture was tilted) and once had another Sony TV that I actually had to adjust on the inside because of this problem. (Newer monitors and TVs actually have controls to compensate for this and thankfully this isn't a problem with LCD displays).