I have this machine and it's an older one. I haven't had that problem yet. I would think it's the foot pedal electrical signal. Not much else it could be but electrical if not mechanical. The problems I have had weren't death warrants but here they are so if anyone has the same.
1. Don't leave an extra spool of thread on the second spool pin. The wheel will pick up the loose end and wind half the cone around it before you notice. Very tedious to get all that thread out.
2. Straight pin somehow got in the bottom of the machine through the reverse lever gap. Jammed up a gear. Removed the pin and kept sewing.
3. Loud pop! Spring on reverse lever popped off and went all the way to the top of the machine. Reverse lever has to be manually lifted up when finished until I can get the spring back on. Sews fine.
4. Bobbin winder slipped, went off track. Straightened it back and sews fine.
5. The bottom and top of machine housing comes off easy and easy to put back on. It's easy to clean and troubleshoot for most all problems.