I have had this problem. With me it is usually the bobbin and the needle. Unthread everything, change the needle and clean out the lint, especially in the bobbin case area. Put in a different bobbin and check with your book to make sure you are inserting it right. Now what I do whenever I change my bobbin is to try it out on a quilt sandwich sample (muslin top with piece of same batting I am using and muslin bottom). I use this sample piece whenever I rethread or change anything. You only need to take a few stitches to find out if everything is correct. It may take a few minutes out of your quilting time but not as long as ripping out all the eyelash stitches.