I have an old Defiant II with a gaping hole where a piece fell out of the lower fireback. I managed to find a replacement part online, but it came without installation instructions. It looks to me as if both the stove back and top need to come off. I have managed to loosen the four screws in the stove back but am at a bit of a loss where to go from there. I haven't found anything in the discussion threads that quite address this problem. Does anyone know where I can get hold of installation instructions?