Originally Posted by Duragrouch

Could be a cheap bushing on the (lower load side) non-drive side.

If it has a cup and ball bearings on the NDS, then the seal was not acting as a second bearing race, the cup was too loose, and thus too much radial force was acting on the seal, stretching it, letting in water and dirt, etc. Clean everything, carefully inspect all balls, if any spalling or scoring, replace all balls, repack with grease, adjust cup until spindle alone when spun in fingers, has no slack (any slack is too loose), is not "notchy" (too tight), but when spun, is smooth, but you feel the balls engaged, that is the proper preload, and under radial load, about half the balls each side will take the load, instead of two or three. That will provide best durability.

When apart, also inspect spindle races for spalling; If any spalling and you don't have easy replacement, mark on the end of the spindle, the orientation of the spall, and when you assemble the crank to the spindle, orient the spall UP when the pedal is forward so will be under load, and pushing the spindle DOWN, this will be smoothest until the spindle can be replaced.

Oh, and I got one of my bikes, used but like new, one crank arm was loose, and this was a bike the seller had purchased new through a dealer; There was a plastic spacer washer there, and two of them, preventing the crank arm from properly seating on the tapers. I removed one washer and put the crank back on, seated perfect. Not sure what the function of even the one washer was for, but left it in place.