Have you checked that your needle is in the right way? I ask because I fixed my DH hunting jacket the other day and when I changed the needle for my smaller needles I put the needle in with the flat side facing to the right. This machine needs to have the flat side facing to the left. It was doing exactly what you say yours is doing. Just a suggestion. I sew and quilt all the time, but have a few different antique Singers and some of them are quite different to thread and needles go in different ways.