Just to ask a stupid question, but could the workpiece have been slipping? How were you holding the wood? I ask, because I have had wood stop when using a steb center. The powerpro is quiet and felt like it stopped when in fact the wood was slipping...
Shopsmith Mark 7, Shopsmith Mark V 1982, shortened, Shopsmith 10 ER; Craftsman table saw (1964); Powermatic 3520B lathe