NannaL,
There is at least one and perhaps 2 capacitors in your machine. They were noise suppression devices back in the day and when they go bad you get a machine that runs by itself. They can be removed without any adverse affect to the machine.
Go to
the featherweight221factory:
http://thefeatherweight221factory.com/Home.php ,
then here:
http://thefeatherweight221factory.com/page43.php to read about the problem and the cure.
Hope this helps.
Joe