I had a Nutone 8832 from the 70's depending on the age of my house that wasn't working properly. The fan motor would turn on, but would not vent properly, often making a loud squeaking or rattling noise. After many repair attempts I found that the plastic fan blade itself was rounded in the middle where it attaches to the motor shaft. It should have a D-neck, but it's probably only worn out for over 40 years. So the fan motor was running but wasn't attached to the fan so it just spins freely. It was a custom sized case, even on today's market, so I should have taken the whole case off and cut a bigger hole. Blanket and cord in a new one that could cost up to $200 and last many hours of expletives. This replacement costs $9 and works great, slips on in seconds and I'm back in a fog-free bathroom. after a nice hot shower.