How do i stop it constantly running?

I recently dug my old (OLD) Frister sewing machine out of the cupboard, passed down to me from my gran. I thought i hadnt used it because it wouldnt work, thinking the motor had died.
I tried it yesterday and when i plugged in the foot pedal and then plugged it into the mains it sets off sewing! now i remember, it wont stop. Is this an easy fix or is it beyond repair and in need of a burial ?

Maxine
January 2009