I have been dealing with this heavy ash build up and a lazy flame for the last two winters. It happens after the stove has been running for a couple days straight or more. I usually just shut the stove down and scoop out the ash, and then restart it. Is this normal? I have used Pellets from B.C. which are a little softer , as well as pellets from the Midwest, doesn't seem to matter. Here is a picture for reference to what I am talking about, took it this morning.