Owner of a 16 year old Breckwell P24 insert. I replaced the motors several years ago and they appear to be working fine. After about 10 hours of working the air holes in the firebox seem to clog around the edges and the draft gets reduced. In short the fire box gets full . I've tried turning the pot on the back of the control board all the way to the left to cut the feed rate, but it does'nt seem to matter. The path is clean all through to the top of the chimney. I just can't figure out why the burned pellets (dust) does'nt exit the firebox. Any ideas would be appreciated.