Try turning off the pump and priming it manually.
Well pump motor humming.
If the pump motor hums but does not start the motor may be seizing may need replacement or a start run capacitor may need replacement.
Worn bearings in the motor shaft can also cause screeching noises when the pump is running.
This commonly occurs if the sump dries out often with exposure of the base.
Chances are it s the pool pump capacitor.
Once you re sure the power is off to the pressure tank you can test with a non contact voltage tester follow these steps to perform basic.
This article series gives diagnosis repair advice for well or water pumps controls tanks water pressure water flow water quantity.
It s possible to change worn bearings though it s far better to simply switch out an old motor with a new one.
If the well pump or control switch makes no noise at all just hums or clicks and when the water pump simply does not run these diagnostic questions may help track down and repair the trouble.
See capacitors for hard starting motors note that some pump motor noise including an unpleasant whine or hum is perfectly normal.
Swimming pool pump won t start pump is humming.
Pump motor humming and trouble starting.
Humming pump suggests the motor was burning up perhaps from over use or there could be a failed motor start capacitor.
The pressure tank and well pump should be wired on the same breaker so if you find a label for well or water pump that should be the power shut off for the pressure tank too.
When a water pump only hums that is it s not moving water the problem could be a bad pump motor bad motor start capacitor low voltage or indeed as you speculate if the pump has lost prime perhaps due to a leaky foot valve it may also seem to be doing nothing but humming a monotone.