Originally Posted by
GrammieJan
When I had this problem recently (loopy thread on the underside) I checked all I could think of. Then I decided to take off the needle plate (the removable plate under the presser foot) and found some lint and a little piece of thread under there. After cleaning it out, all was well then.
I'm not familiar with your model of Singer, but I have a Singer H74 that has the spool post on the horizontal--I find when I use the optional vertical spool post I get better tension. Also when my bottom thread on the Singer or my nice Elna, it's usually because the top thread has come out of the take up arm or the tensioner discs--maybe from "jumping" a thick seam intersection,etc.