Zed Head, I understand your concerns. My thinking is that there must have been a minor scratch or build up on the spindle, it was a little discoloured at the outside edge where the inner bearing sits. I was very gentle in my sanding, and would consider it more of a polish. Neither the old and new bearing wouldn't slip on until I did the polishing. My approach was to give it a few rubs, clean with brake fluid, apply and then try to work the bearing on. The place I was polishing was right at the edgeof the big step, the inner bearing wouldn't even start to slip on. Where the bearing rides wasn't polished. I don't think I did too much damage, the bearing is still tight aginst the spindle.
Steve