I have a Statler Stitcher and a couple of years ago I was ready to roll the machine out the door to the curb! For mine was doing horrid stitching also. I tried everything for days on end. Then out of the blue I changed bobbins, and it stitched just fine. On closer exam of the bobbin itself I found that it was out of round, and it was a brand new bobbin! So that bobbin went right to the trash. It could be something as simple as your bobbin itself.