We may have found other answers which could help you.
Click here for Delta Sewing MachineToyota SL3404D Overlocker leaving big loops?
How to switch on light of sewing machine?
Frister & Rossmann cub 7?
How can I mend my Frister & Rossmann sewing machine?
Sewing machine issue?
Singer zigzag 457 Stylist not threading bobbin/making stitch?