Hi, I got a st. Croix pellet stove that came with a house I had bought but has no manual. Lately the stove doesn't seem to push as much heat out as it did the first time I used it. The flame will die down than shoot back up to the top of the stove along with shooting sparks everywhere while it's in the process of turning the glass black to the point I can't hardly see anything so I have to clean it every time I burn a bag. So I'm curious what I'm doing wrong.