Originally Posted by Jratcliff

I've had the same thing happen, but not from lack of screw tightening. It is when my threads get caught in the bobbin and the machine doesn't stop, or one time when the thread cutter didn't cut the threads and the hoop moved quite a distance.

To the birds nest, I was talking with a friend who said she had the same thing happen and always when she used Sulky thread. She changed to Madiera and it quit. Of course, Sulky is what I am using right now.
The other thing she said was, the person that sold her the machine said to use just a touch of lubricant on the needle from time to time and it would stop. He attributed it to sticky build up on the needle from going through the stabilizer. She also said she finally gave up after her third machine and went to a 6 thread model and it hasn't happened since.
I'm not ready to go that route. One reason is the cost, and the other is I'm not in this as a business - just for my own use and fun.