Hello Joyce,
First thing to do is take the bobbin and bobbin case out and make sure there is no thread jammed in the raceway, that is the usual cause, before you do that release the stop motion and see if the balance wheel turns, if the balance wheel does not turn the belt may have come off and jammed but I am still convinced it is a thread jam
drivewithken@blueyonder.co.uk, March 2008
