Before the heating season comes I will likely have to put a liner in my masonry chimney. It is the rectangle 8 x 12 " nominal tile liner. I think I am missing a joint between the tiles and some creosote is running down on the outside of the chimney, I think the damage is close to the attic/roof line. I have a newer woodstove with a 6" pipe connection. My chimney is 25' from basement floor to the top. I have excellent access, and flex or rigid liner should be very straightforward. I have been doing some leg work, but would appreciate any help you can offer? Hoping someone here has some experience to share? Thanks, Tom