My range hood has stopped working. The light works, so I know there is power. But the on/off switch for the fan doesn't turn the fan on. I have pulled the fan itself and it seems to turn freely (by hand). In looking at the mfr's parts list, I realized that I have no way of knowing exactly which part is defective. Do I just replace the whole control box, or could it be the motor? How do you test for thses things?

Also is the a single part number for the control assembly - as opposed to each individual part on the exploded diagram?

Thanks