When I sew, the bobbin thread bunches up and the seam doesn't hold. You can pull it all out from the bottom seam. It seems to be the tension but I can't get the tension to adjust.

Gail H., October 2008

Hello Gail,
Make sure the presser foot is up when you thread the machine so the thread goes completely between the tension discs, top tension should be about 5, you should just about be able to pull the bottom thread through with some slight resistence, if it is too tight it will pull the thread through, if it is tight just slacken the scew on the bobbin case ant-clockwise about a quarter of a turn at a time until you get it right, remember that Singer machines are best with mercerised thread no thicker than a number 40.
Ken

drivewithken@blueyonder.co.uk, October 2008