I can try to solve most sewing problems.
Kelley Buchanan posted an answer for this White Sewing Superlock 1934D Mechanical Sewing Machine:
"Sounds like your machine is either out of time or the needle isn't in far enough. I am..."
Kelley Buchanan posted an answer for this White Sewing Speedylock 1600 Mechanical Sewing Machine:
"If there is a joann fabrics store nearby, they have them. I think you can also order them..."