This is kind of funny. I just brought my machine into the dealer to get checked out again. I've been having issues with the tension. The last time I brought it in, one of their instructors told me to never adjust the tension, just use the built in preset buttons and the tension would be set automatically. However, I told her if I do that I don't get a nice stitch. But don't change the tension, she said, "You'll just get yourself into trouble and make it worse!" When I spoke with the repair fellow, he told me, "She's just a teacher, don't listen to that. Sometimes you have to change the tension with different threads and fabrics you're using." I do keep a written record of what settings I have the machine at for each kind of thread and fabric. I also did purchase a different bobbin case for use with thicker threads.