The last rebuilt starter I bought was several years ago for the 88 Ford gasser pickup I had at the time. It seemed fine at first but after a few months it got to the pint where it would barely turn over, sometimes not at all.
I removed it and when I shook it sounded like a bucket of bolts. Upon further inspection the bushing at the end of the drive gear was so far out of round that it was cocking the internal part of the starter when it engaged, hence locking it up.
It was total junk and I refused a replacement from the parts store because originally I asked for the best quality unit they sold. I got my money back and never bought another thing from them.