Do not improvise an alternative electrical supply around wastewater equipment. The appliance and installation need appropriate assessment.
What the observation means
An extension can introduce additional exposure to water and does not diagnose the original fault. Moving the unit to reach another socket can disturb pipework.
A useful next step
Keep connected fixtures unused if the pump cannot operate reliably. Describe whether other equipment was affected by a known outage. Do not change fuse ratings, run a lead through a wet area or power the motor directly to empty the system.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.