The woman I just bought my new machine from said cotton thread is too liny for machines. So, I bought polyester. BUT, a dear friend gave me a gift today--and it's 3 large spools of C +C cotton machine quilting thread. :D :wink: They didn't have polyester in big spools--just teeny ones. So...I'm going to use it and just hope cleaning the bobbin area helps. :?: