HS Tarm wood boiler bottom door seal

forester

I purchased a HS Tarm Solo plus 40 in 2006. It does a great job in heating our home. The problem is the boiler cement seal on the bottom door. The bolier cement seal is subject to temperatures at 2000 degrees plus. The boiler cement that i have tried (includes many different brands) eventually cracks and falls out. The company is now suggesting I use a gasket between the boiler jacket and boiler body and a gasket and boiler cement between the jacket and door frame. Has any one had this problem and how did you correct it?