| Possible causes | Recommended action |
| Bearing is damaged. | Replacing bearing |
| Excessive discharge quantity. | Adjust the water volume to the specified level with discharge valve. |
| Impeller is clogged. | Remove the foreign objects from the pipe. |
| Rotate in the opposite direction. | Follow the arrows to correct the wiring. |
| No-discharge operation for a long time. | Stop no-discharge operation. |
| Roatating part contacted.Or shaft is bent. | Repair at a specialized factory. |
| Cavitation is being generated. | Consult an expert. |
| Resonance in pipes. | Improving piping. |