Bathroom fan and blower wheel noise

I have a bathroom exhaust fan that recently starting making noise from the plastic impeller. It seems as though the plastic fan blower wheel is unbalanced and making a rhythmic thumping noise. I just don't know what is causing this or how to tackle the problem. I cleaned the impellers of gunk but the same noise continues.

You can listen via the link below (no signup req'd if DropBox asked you to signup or signin just cancel and you should be able view/listen.

Listen to video of bathroom exhaust fan
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If anyone has an idea as to what is causing problem and how to fix, I'd appreciate any advice.
Thanks!

 

It sounds like the blower wheel is loose on the motor shaft. It's only plastic and may be worn.
Even though that's an older fan there are parts still available.

Broan/Nutone has replacement motors, wheels and kits of both.
Look for the ID tag and post the model number.

Example wheels

 

Ok. I finally found the number. Not sure how I missed it on a huge label. Pete, if you have a suggestion on a separate part or a kit that I should get, please let me know..

NuTone QT-9093

Thanks!

 

Just replaced the blower wheel for same reason. Simple job. Cost less than $10.

 

That's a heat, vent and light unit.
The part number for the vent blower wheel only is 51919000.
Search using that part number.

Broan/Nutone - complete parts list for QT-9093
motor and wheel only

 

Thanks for the info on likely problem with the blower wheel and the part number. Much appreciated..