hope someone can help with this problem. as you can see i'm running a old defiant. the secondary in this old stove runs well but it's still smokey. better than running in updraft mode. it cuts the smoke down 3/4. i tried a experiment and it worked. the smoke is coming from the damper area not being a tite seal around it self. what i did was put some door rope gasket in the spots where there was a gap. for awhile it was almost smokeless burns. small hot fires were smokeless. my problem is the rope gasket is not taking it so well the funace cement that i used along with other garbage grinds it up. does anyone have any ideas on a gasket that is thin yet strong. thanks