NAPA used to sell rebuilt starters from one of their own rebuilders that would typically have pieces of brushes etc fall out when you shook them. dirt etc. I got the impression that they bench tested all the ones that came in and if they passed the bench test they had someone clean them off and put them in a box and send it back out. They had 3 levels and prices for their rebuilds. Even the second level had reused brushes and reused passable starter drives. the one with the best warranty was a pretty good one (usually) and had lots of new parts and was well done. just sometimes you swore that they ran out of the right boxes and upgraded lol. People who knew that would inspect them at the counter and shake them to see what fell out.