I am going to be looking at a Jotul F12. Can anyone give me any advice on what to look for? For instance, how can I check the cat. The lady said she used it about 40 times total and it was bought new in 1997. She did disclose that one of the door glasses has a small crack in the corner. Where can I source new glass for it? I looked at the manual for the unit and it says it's 27.5" center for rear exhaust, and my existing opening is 26", so the duct would swoop down before entering the existing masonry chimney. I will be building out the hearth to accommodate the stove, although I didn't see any clearance measurements in the stove manual for the bottom. here is the pic she sent me: and here is the existing space.