I decided to take advantage of the mild temps on New Years Eve and clean out the stove. Thought I'd even empty the ash pan and maybe try removing ashes with it for some time and see if I preferred that over scooping them with the ash shovel. Sat. and Sun. I was constantly stalling and re-starting my loads. It was downdrafters hell. But why? All systems were go when closing the bypass. After two days of ash buildup (still not a full pan, but getting there), I finally have gotten her acting her old self. I can only guess that ash acts as a terrific insulator to keep the heat from being lost to the bottom of the stove-as I've read here at Hearth over and over. Never doubt the benefits of ash in the bottom of your stove.