The Bernina Stop Motion Wheel 0018937201 is a vital component. The part is designed to be used on the 1000 Series models. That means the 1005, 1020, 1030, 1008 etc. etc. You would normally loosen the stop motion wheel to disengage the drive, and wind a bobbin.
His close friends include a small screw, which screws into the hole you can see. This small screw also stops you from completely removing the stop motion wheel. And a friction washer which fits onto the balance wheel bush.
Berninas in Schools
In days gone by, this was often the part that went missing when we serviced Berninas in schools. Or, quite often there would be two yards of sewing thread wrapped inside. Every now, instead of thread, we would find hair. Someone with long locks would have leaned a little too close while the machine was at full pelt and…. Ouch!!!