Would a worn spring cause a slight pull? My thought is that after years of single driver operation, the spring gets slightly more worn on the drivers side, causing a little dip on that side and maybe a tendency to pull. I'd rather not adjust to compensate for that, but maybe it would make things a bit more balanced if I do change springs.

I've heard it is unwise to swap springs to different positions, that they will crack due to changed lateral stresses from the mounts. Is that true or only in very heavy vehicles?

Thanks. You seem to know alignment stuff really well.