PREMIUM GRADE DOOR SEAL FIRE ROPE
Many sellers claim their fire rope is adequate for your furnace - but if your door gasket is 1" wide, there is no better fire rope than this one.
Door Seal Fire Rope: Used to seal firebox doors. Ships in 10 ft. lengths, but may be cut to fit as needed.
Specification meets ALL Hawken model furnaces, among others.
Installs easily with Hi Temp Black Caulk, available at this site.
See this link for instructions on how to change the door seal: