Speed of my Singer 201?

I have a Singer 201 manufacture on feb 12 1941. My Mother had it and my parents had 4 boys. I want to keep machine but the speed of the sewing needle is only one speed.Slow, I suspect the foot switch needs work.The switch says Sewing Motor Controller. 95-145 volts Part No 195325It has a porcel cover and inside there is a plunger. How can I rebuild this.