Have you ever used the "fully enclosed - with metal Front and Backside" Main Drive Gear Seals????? They press in really hard, and they're almost impossible to remove with sheet metal screws. I think it's because the backside is enclosed, and they can't crush a bit.
I chucked it in the lathe and cut the back side out . . . now it should press in with a reasonable amount of press fit, and I can still get it back out with "a reasonable amount of effort." It's like the old style stock seals now. Remember: Always install your seal with the inner seal spring towards the oil, or on the same side as the oil you're trying to keep from coming out . . .