I have had my stove for over a year now and I know that taking the back panels off behind the fire brick to clean the passages for better air but tonite when I shut it down to clean it I stuck my fingers up by the heat exchanger tubes in the front of the stove where the scraper is and felt a bunch of ash,so as you pull the knob to clean the tubes you are just pulling ash and compacting it to the front of the tubes,if you feel towards the front of the stove you will feel all of the ash that is compacted, I cleaned it all out with a small paintbrush which I cut half of the handle off of to get it up in there and now the stove runs alot hotter,just something to check I guess also if you take rope gasket and plug the air wash channel you won't get as much ash on the exchanger tubes which will help this problem,stove is hot now with more air moving around the tubes.