I also had an E6 error on my Brother machine that wouldn't go away after cleaning and rethreading. I bought a really good artist's brush and took apart the bobbin area and cleaned it out thoroughly. the brush that comes with Brother machines is useless as to collecting all the lint in the bobbin area. but the artist's brush got out extra lint the machine brush didn't and even found a tiny piece of a needle that had broken at some point (the machine had been sewing for quite some time with this little piece down there). I put the bobbin area back together and rethreaded the machine. lo and behold - it worked!!! the E6 error was no more. so try this before giving up. good luck!