I have a Necci Omega sewing machine model #6018. When I sew the needle thread and the bobbin thread are not interlocking correctly on the bobbin side of the fabric. I can pull the bobbin tread loose from the stitching. I have tried the trouble shooting suggestions from my manual for "stitches form loops below the work", but this has not corrected the problem. I have the stitch lengh dial set at 2 and the thread tension dial is set between 3-4
Sewing Machines - Necchi - 6018 Mechanical Sewing Machine