Folks have been known to crack open the ash pan drawer (on those stoves with open ash grates) to let some air leak in under the coal bed and give the fire a boost. The ash grates were exposed to those white hot coals and would often deform. Especially when the operator got too aggressive or forgot that he cracked open the door.
Be sure that the ash plug sets done fully in its bore and even dump a little ash over the plug to be sure it's sealed off well. The bk requires that metered air from the stat only, all preheated, to operate as designed.
