| Possible causes | Recommended action |
| Excessive rotation speed. Wrong Pole number of electric motor. | Check nameplate and replace the motor. |
| Higher voltage | Check the power supply |
| 50Hz pump is running in 60Hz area | Check nameplate and replace the motor. |
| Pump head is low. Excessive discharge quantity. | Close discharge valve to the specified water level. |
| Bearing is damaged. | Replace the bearing. |
| Roatating part contacted.Or shaft is bent. | Repair at a specialized factory |
| Excessive specific gravity and viscosity of the liquid. | Review the plan |