I thought I did explain it. The drive shaft goes into the double-D hole in the upper cap on the shock absorber. The upper cap is fairly thin at the top end–in fact as thin as the wear notches on the drive shaft. The drive shaft is fairly soft in comparison to the shock absorber, which is very hard. So, the shaft is exerting a rotating force in the shock absorber’s double-D hole and the softer shaft just gets beaten away, for lack of a better word. It would take a motor with very few hours on it to show no wear. The more hours, the more wear. I suppose a low oil level might contribute to it a bit, also.
