Sounds almost like wire riding on top of fan. I looked, nothing touching. If you run the fan on high bad noise that was not there before. Under warranty until April 19. Bad Motor? It's been building to this level of noise The Fan blades are clean (just cleaned them after noise started). They were clean. Exhaust Motor is not loose. The unit got full cleaning about 2 bags of pellets ago (few days). It's only run 1/2 ton of Pellets and was new (floor model) stove. Went back and Cleaned Exhaust Blower again. It's going thru startup right now. Hate to call them out for service charge and it's nothing. It was not very dirty, but not all blades the same. The same now. No balance in blower fan that I can tell. After firing up the noise was there again, then after 5 minutes it went away in space of 30 seconds. Update: After 30 min it started again (Noise). When LED comes on for Distrib Blower noise starts. It's the LED's Fault I bet! Still will talk to dealer. I have video, but can't upload here.