This is the noise that the room / convection fan Is making on my St. Croix Hastings pellet stove. I am looking for feedback from the forum on hearth.com as to a fix without replacing the whole unit. This started after I did a thorough cleaning. Everything (and I mean everything) except the "leaf blower trick" and removing this fan. I actually thought that it was the combustion fan making the noise at first since I disassembled it to clean it. The only thing I did to this fan was run my shop vac next to the grates to clear some dust off. After I realized the this fan was the issue, I removed it and totally cleaned it with brushes, compressed air and a shop vac. I don't think the noise is as loud as it was before I did it. This video shows the noise after the unit was removed and cleaned.
http://www.youtube.com/watch?v=0Mg2QUcYMwI&feature=youtu.be