About 25 years ago, my parents installed a chimney on the house from the basement. They used the double walled insulated stainless 8" stove pipe and once outside at ground level they put brick around it clear up until there's only 4 feet or so that doesn't have brick around it at the top. They have a horizontal cleanout at ground level with a stainless lid on it. My question is, how concerned should a person be with replacing the stainless stovepipe that's inside the brick? The "T" that's at the bottom for the cleanout has over the years deteriorated and the inside stainless layer is gone on the "T" and you can see/feel the insulation of it. I dont even know how a person would go about replacing the T or any of the piping without tearing apart the brick chimney. Or should a person not worry about it since it's inside brick on all 4 sides?