if its a electrical pump there is an easy way to do if you carefull not to get electricuted.strip the pump assy off and put some tape on one vane,after connecting power hold your finger close to tape to feel if its turning a full circle and not just agitating,it does happen sometime that the pump motor sound like its turning and meanwhile just moving back and fro around the axle.also check impeller for security of attachment
jj
March 2012