I had a pedal like that get destroyed when I was transporting it over to a friends house to weld up his car chassis. It had apparently fallen off the trailer and had been getting drug for god knows how many miles. I noticed it when a song stopped on the stereo and I heard a grinding noise. When I looked back, I saw it dragging about 20 ft behind the trailer. What made it worse was that I had just purchased a new resistor block for it that cost me about 60 dollars. Ironically when I got to my friends house, he had one that someone had given him.
To make a long story short, I called the Miller Repair place, and they can get them and they were around $300. But they wouldn't be hard to make, you'd just need a limit switch, a Resistor block and the wiper. then just make a foot pedal.