Hello Alan,
I take it that you are talking about the stop motion wheel on the end of the machine to stop the machine working when winding a bobbin ?
What normally happens is after winding a bobbin the stop motion wheel is turned back too far and the screw pin goes the wrong side of the three pronged washer that is inside the stop motion wheel, look at the stop motion wheel and you will see a screw, it may be covered over by a label so run your finger round until you find it, slacken the screw off, turn the stop motion wheel anti clockwise about a quarter of an inch, tighten the screw back up and it should be okay, any problems let me know.
Ken
drivewithken@blueyonder.co.uk, August 2007