The hand wheel does not turn, is very stiff to move?

Helo Christine,
First of all turn the balance wheel backwards just in case there is thread stuck in the raceway which is quite likely, to make sure it is not a belt problem undo the stop motion as if to wind a bobbin and see if the balance wheel turns freely when you put your foot on the control.
Take out the bobbin and bobbin case if you can and wipe the raceway area with a cloth, if you still have problems e-mail me with your make and model.
Ken

drivewithken@blueyonder.co.uk
April 2008