I have a Janome 6600 which despises my Gutermann thread. It will clog up and make huge birds nests over and over again. I took it into the shop about 2 dozen times when I first bought it. We finally just decided nothing was wrong with the machine, it's just very picky about thread. I've had to change to Aurifil. I have so many spools of Gutermann, so I just use those on my Featherweights.