Put your hand on the motor when it quits. Be careful. If it is real hot then I would say a bearing has failed in the motor. Time to get a new motor. The good news is they are easy to replace. Of course their could be a stray something or other has gotten into the pump and caused it to lock the motor up. Like strings from a rug maybe or a baby sock, string bikini,thong,coin,sand, etc. I live near the beach and sand is a big issue around here.