After a thorough cleaning of both the case and the doors, we used MP-7 to prevent rust from ruining all our cleaning efforts. At this point, we began the reassembly. We tapped the retainer for the fresh-air door flat to allow it to slip over the rod. Then we applied the foam to the heater parts using a good quality trim adhesive such as 3M 80080 or 80013. Since the case is black, we used 80080 because the color is the same as the case.