I got a pellet master for free years ago, it needed a new auger. I welded up a new one and installer it. I usually don't use it that much since it's in my garage. It's always blackened up the glass and the heat output seems low. I've checked the gasket and the combustion fan seems strong. I've cleaned it many times hoping it would help. I don't use it that much, but but the air coming out of isn't as warm as I thought it should be. I'm getting my pellets from the local menards, only place that carries pellets. I would really like this to put out some serious heat. What is my next step?