My pool pump (Pentair Whisperflo) wasn't turning on (would only make a humming noise when I flipped it on), checked the capacitor at Grainger and they said it was good. Went back and pulled the motor from the pump. When I removed it, the seal plate, diffuser, and impeller were still attached. The diffuser looks fine, removed it to view the impeller. I tried turning the impeller/shaft and it was a bit hard to turn, once I removed the impeller the shaft turned MUCH easier. So I tightened the impeller back on and again it was difficult to spin. The impeller seats into the seal plate and on the inside it looks like it has some type of spring in the middle that the impeller sits on/in. Could that spring or something in the seal plate be causing my impeller/shafts not to turn?