I just purchased a used EF2 pellet stove insert from a friend. I installed a 4" stainless liner in the existing masonry chimney just like the manual showed. The problem is that the flame seems to be like a blow torch and not like the recommended pictures. There are sparks flying everywhere every time a pellet drops in the pot. I have the slider completely closed and when i connected a mag to the test hole, the needle pegged past -.25". My question is how can I turn down the combustion fan so I can achieve the recommended -.12"? Is it supposed to turn down automatically and something isn't working correctly? Everything I have read, the combustion fan doesn't change speed. Any help would be appreciated.