Air lock on start up, if so... Purge air out of pump
Purge valve open, if so... Close purge valve
Pump suctions plugged, if so... Clean suction
Burnt out fuse, if so... Replace fuse
Pump thermal over load, if so... Require better venting
Hi-Lo reversed, if so... Reverse Hi-Lo wires on pump
Pump cord, if so... Replace cord
Faulty pump, if so... Replace pump
Faulty control panel, if so... Replace panel