Search FMQ on this board. There is some awesome advise here that helped me overcome the exact frustration you are having. I have a different machine than yours, but I can tell you this ... If the thread loops on the bottom, your top tension needs to be increased. If the thread loops on top, your top tension needs to be decreased. Very seldom do you need to adjust your bobbin tension. Use the same thread in top and bobbin. Do not use cheap thread. Use a brand new needle. Look for lint in and around your bobbin case. Make a sandwich of exactly the same quilt fabrics and practice! You'll get it and it's SO WORTH THE EFFORT! Don't forget to breathe!