I have a wholehouse ventilator, which is a 36" fan that sucks cool air
through the windows and pushes the hot air in the house and attic out
the soffit vents. Much cheaper than running the A/C. Here's the
problem.

I recently had a contract working near it doing some drywall work. All
he was doing was feathering in some mud and texturing.

Before he was here, it worked. Now it doesn't.

When I turn the power knob, I can hear what I perceive to be an
electrical current going to the motor. I'm pretty sure there's juice
there.

I just can figure out why the motor won't turn?

Any ideas at all?

Thanks.