Ok, so here is the situation. Once a week i've been taking all the baffles off and shop vacing behind them and behind that hole on the right side baffle. Cleaning the tubes really good. And every few weeks I will go out side since I have a horizontal exhaust and take my shop vac and turn it on and run the hose all the way up a few times. Once I do that and start it up it burns like normal ... but it seems like every 10 or so bags the flame is getting higher and the pellets start filling up more. I mean not alot, but just below the first combustion hole. When I do my weekly cleaning it doesn't do that until like the 10th bag or so. And when the pellets get that high it makes like a small humming noise. So is there something i'm missing in my clean up ??