Asking for help. My EKO 40 is five years old. I clean it at least once during the heating season here in New Hampshire and after the end of every season. At the end of last year's season, I started getting an "E-2" code on the display panel - not "Fuel". I found several pieces of wood I had loaded (filled the wood chamber up completely each evening), blackened, but not burnt. When I loaded a partial fill, usually half way, the unit burnt all the wood and performed like it always had. I cleaned it again after the last season and then again before this season. I think I am missing something. I have not "tweaked" the settings as they have worked for almost four full heating seasons. My wood has been seasoned for 9-10 months at least. Any help would be most appreciated. Ed