Convection blower started to make a humming, straining sound ,sometimes no air would be blowing at the # 1 low setting then it would come on or if I increased the speed it went away. This seemed to happen on start-up more that if the stove was running for a while. I ran 24/7 Dec,Jan much of the time on low no with no problems If I did use T-stat I left it on Medium speed.Last week stove was running on medium speed and I smelled like hot metal smell from the other room found that blower was not working , played with the speed settings it came on and I shut the stove down and called the dealer, he installed a new blower yesterday, this morning I hear kind of the same noise again, speed it up it goes away. I put a srewdriver on it and I can feel the blower kind of shake when the noise appears. Am I dealing with a vibration problem or do you think something else ?