Englander 25pdv incomplete burn

[boss7t]

I am having the following problem with my Englander:
Starting with a clean stove and chimney, blower on 9, feed rate on 5, the pellets in the burn pot burn until the ash is gray and the pellets are completely burnt like you would expect. I also have a Harman XXV and the ashes match in appearance at this point. The problem is that longer the stove burns, the less completely the pellets seem to burn. After a good 12 hours or so, the ones that are immediately exiting the auger are burning and in the rest of the burn pot there is a bottom layer of red hot pellets with a top layer of blackened and burnt pellets that still hold their shape and are not on fire. This will continue until they pile up against the door. The stove is in a basement with about 10 feet of 3" vertical chimney, a tee, and three elbows. Outside air is supplied via a 2 inch pipe. I would suspect an air feed/exhaust problem except for the fact that this will burn for 12 hours or so just fine - completely burnt pellets and a fine ash. I would suspect pellets but they burn in the Harman just fine. I had it on a thermostat and replaced it with the jumper as I wasnt sure if this was the problem. I am currently using the jumper.
Any ideas?

 

[becausemywifecanoperateit]

mine does to........only after i switched brands of pellets though........you say the pellets burn good in your harman ......that cake of red hot pellets does a good job of cleaning the hair off your knuckles don't it?...........i wish the wear plate didn't tip up so much.......then some of the junk could be ejected...........i think more combustion air would help after seeing another stove in action.......pretty wild flame movement and it seemed the lighter debris was blown out of the burn area.........

 

[boss7t]

Yeah, no more pesky knuckle hair. I was thinking about turning that wear plate upside down or something. It really does seem like with a little more air this thing would really cook.