Note: The most frequent cause of pump failure is that customers miss the part in the instruction manual (pages 9 and 10) about taking the pump apart to clean it. If the fountain is quite new, the other cause is that the impeller in the pump can come loose. Going through the procedure for cleaning the pump usually will solve that problem. After Reinserting the impeller give it a couple spins with your finger to help ensure it is properly in position. Put pump in some water by itself and plug in to make sure it is functioning before reassembling the fountain. ***After Reinserting the impeller give it a couple of spins with your finger to help ensure it is properly in position. Put pump in some water by itself and plug in to make sure it is functioning before reassembling the fountain.***