Here is a simple video on "How to check your thread tension." There are two tension on every sewing machine. One on top, that you can adjust as you sew and one on the bobbin case. Most often you will make your adjustment from the top to correct any issue. The top tension should be at 4 - 6 setting. The zero setting should let your thread pull through with out any tension at all. Remember to lower your presser foot. If your presser foot is up it will not apply any tension. A quick check on your upper tension is to take it down to zero and pull on your thread. It should pull through real easy. Then move your tension up to 10, now it will be real hard to pull. If fact you might break the thread. Then take it back to 5 and pull it again it should be between those to settings. If you set your dial to 10 and there is no tension you need to have it serviced. Watch the video for more information. I will share more later on on the bottom tension on how to check them.