I bring all the coals to the front and just load splits on top. If I get too many then I'll bring to the front and put a few pieces of my pallet kindling on top with full air open and let them burn down a little. I don't really have this problem if I keep moving the coals to the front because they burn off pretty good with regular splits. Wet wood would keep huge coals (sometimes still in log form). I realize that you say it's seasoned, but wonder what the moisture is on them. A lot of times 2 yr old wood can start getting a little punky and pick up water and keep it. Bet if you line your chimney you'll see a huge increase in performance. These things have to have a good vacuum of air coming in.