My sewing machine works fine, and in fact I'm so ignorant about sewing machines, for all I know it IS working fine. The problem I'm thinking I'm seeing is that after sewing a line, I can easily pull on the "top thread" (the one which came from the spool) and it slides right out from the grasp of the bottom thread (which comes from the bobbin.) I do recall testing the sturdiness of the stitching from this sewing machine before, and being surprised that I could NOT just pull it out from the material. In other words, I do not recall the thread behaving the way it is currently when pulled upon.

I have experiemented with different tensions. The straight stitch which I'm doing lookes prettiest and most consistent on a setting of 5. However, on any tension setting, I can still easily pull on the top thread, and it comes right out.

I have located the manual for this old CM-17C singer machine. I downloaded it and do not see anything about setting the tension for the bobbin. In the area of the bobbin I do not see any screw heads which might be turned to set tension on the bobbin. Unfortunately the illustrations in the .pdf file are a mess. They did not scan well to the new format.

I did sew a line and then tried pulling on the fabric (not the thread this time), trying to pull the fabric apart (pulled perpendicular to the stitching). The line of thread did hold up well to the pulling, so well that the fabric tore before the stitching gave way.

I'm yammering. Can anyone gimmie some hep?