Why does my sewing machine race fast once I touch the foot pedal?

I have a EuroPro computerized machine model 9105, about 12 years old. Has worked perfectly until now. I'm getting various results when I press the foot pedal, from no action to my machine racing very fast. Once this starts I have to turn off the power to stop it. I thought it was the pedal but I tried out a new one and the same occurred. What is going on and will this be repairable? Help