Originally Posted by dwood

Straws,

With any sewing machine . . . and particularly heavy duty ones . . . it is necessary to hold both threads securely until you've completed a couple of stitches. Holding them down with one finger often isn't enough. I actually wrap a turn or two through my fingers and hold on tight.

What you describe is exactly what will happen [most of the time] if the threads are not held.

DON