Good to know. I was thinking that I could probably take the flue collar off and get more room to reach the damper gasket that way, but if the entire back casting comes off easy why not. I imagine I need to get that off to replace the refractory anyway if the upper fireback doesn't come out...... I see what you mean, it does look like getting the upper fireback out would be a real *(&^^ even though its smaller in the 2550. The stove heats just fine and Im sure I could get a few more seasons out of it before the refractory is totally shot.... but I know its getting to be due and Im crazy enough to want the challenge.