Either the front half of the pump has come off (part 6045.130) and the pump just needs to be removed and reassembled (this is very common in shipping and very likely if this wasn't checked before first use). Or, the propeller itself has seperated from the magnet that drives it, it clicks onto the shaft of the magnet and it should fit very stiffly so it is firmly engaged when the magnet turns. It should not come off easily, if it does this part may be damaged or defective and we can send a new one. It is also possible that some small bit of sand or packing material has jammed the magnet in the pump and simply removing it and rinsing it should get it going.
