Loud Screaming!!

Try turning the impeller by hand (one finger should do it) with the machine off to see if you can feel any drag on it.
This thing should turn very easy and rotate a little on its own if you spin it up a bit. They are normally not directly driven but propelled into rotation by the force of the water which is dependent on a recirculating pump
If it shudders to a stop, the primitive 'bearing' may be worn requiring replacement.