Old stove that came with the house we bought this summer. Chimney has been cleaned. Stove has run fine since October. Backplate was bowed with a crack in it which still remains obviously. As of today when I go to load more wood it billows smoke out this back top corner as far as I can tell. Crack in the stove? What would you suggest. Had been firing it hot with this cold routinely up past 600 degress plus before I close damper