Ok so I found some time on the weekend between yard work and car work/ oil changes to start the final interior cleanup. I got most of the loose buildup off already, now the goal is to remove all the remnants of furnace cement from the upper fireback mounting surfaces and clean it down to bare metal so the new one will fit and seal right. Plan will be to dry fit the upper fireback into place before installing the refractory or gasketing. I figure once that's all done I have only one shot to get it right if I'm cementing it. As with previous jobs, a dremel with a variety of grinding tips is almost a mandatory tool for this work. I put the shopvac outside with a long hose coming through the window and work two handed holding the dremel in my right and the vac hose in my left. Don't forget the mask and goggles too. A couple findings... First off, the lip at the top of the back sating that the top edge of the upper fireback hangs off is actually a half round groove like a gasket channel. Defiant, I know you stated before that you gasket the sides of the upper and glue the top edge? Or could I put a gasket in this top groove and avoid cementing it in? Secondly a lot of the cement in the vertical seams between the back and sides was loose and falling out. If i had the luxury of time it probably would not have hurt to take this stove out of the house and break it down all the way but I cant start into that now. The back casting actually has a 1" flat overlap on the side panels with what looks like a double tongue and groove seal so I'm hoping this is not critical. I will grind all the loose cement out of the channel and lay in a new bead of furnace cement from the inside as insurance however. Not ideal but better than leaving it as is.