I just bought an 80's hearthstone II with rear flue exit.. I have the top, door frames, insides and about half of the soapstones removed. My big problem is that I dont know what (if anything) should be between the inner and outer iron plates that bolt togather for the flue pipe to slide into.There is morter inbetween the iron plates now, but I dont know how it came from the factory. There is a piece of steel flat stock between all the pieces of soapstone where they butt togather, there is also two flat stock pieces in the stones surronding the flue( like a piece of soapstone with a hole for the flue pipe wold be). I looked at the parts diagram , it does not show any such stone, just the inner and outer iron plates. I want to reseal this stove and get it burning again. Any help would be great.