I have been working on a couple of quilts. We have two sewing machines in our home. They were BOTH skipping stitches, by this I mean they'd sew fine for a few inches (straight stitch) and then it would run one long stitch. Like this:
_ _ _ _ _ _ _ _ _______________ _ _ _ ____________
I was getting so frustrated. I adjusted my tension, re-threaded both the top and bottom and it still skipped.
THEN...I checked a couple of troubleshooting websites on line and found my problem! Praise the Lord! HERE is another site about needles.
The needle I was using was a 16, this is because I had been sewing denim and some thicker projects. So I changed to a size 11 needle because I am sewing regular fabric and it is sewing so wonderfully!
When sewing several layers or think fabric, such as denim, you need a larger needle, otherwise it will break. I learned this lesson the hard way too!
Sewing will test your religion. ;o)