I have a Liberty Sewage Pump Model 372/LE41A and I don't hear the water pump but all I hear is a humming sound . I have tried something else in that socket and it worked, could it be the switch.

Thanks, T

That sounds like the pump is trying to run but can't. Or it sounds like the pump is running but there is nothing there to pump. Or it could be the pump is running but can't move any water because the discharge line is blocked.