Can anyone describe how the heated air flows from the firebox point in the above stoves? I know in the Harman Advance I had, it went up from the firebox, then behind the "brick" panel, and the small panels in front of the accordian heat exchanger in the back, down to the combustion exhaust blower. In the P-68 I have, I see the accordian heat exchangers on the top, but I'm wondering what the path is to the combustion exhaust blower. Any hidden surfaces to clean, or just brush off the inside of the visible stove??