Hi John. In terms of troubleshooting the humming sound, do you hear it from the fan when the fan is turning?
Generally this is a sound that all fans make, but there could be certain situations where the sound is being amplified by the fan housing, or the blades, or something else. It’s important to understand if the humming sound happens when the fan is turning; if not then it’s not the motor specifically and something else.
Here’s an article that should help you to troubleshoot the humming sound. Let us know how that works out for you!