Yesterday I cleaned my chimney. Its double wall pipe. I used a soot eater and it knocked down alot of the build up but not all. So I tried again with a 6 inch poly brush. It got some more off but there is still a small amount of build up, maybe a 1/16 -1/8" in some spots. No tar dripping type build up. Is there anything else I can do? I'm not against calling a chimney sweep to do it but want to try myself first.