I've never seen that happen before. I've used FasTrack for over ten years. There must be a defect in the casting. Are these new? An option is to unbend the tabs on the bottom of the track for the center rail and remove the rail to the point you can get the pin out. Then you can use an ordinary tubular track pin in place of the broken FasTrack pin. If they are relatively new, I would ask for an exchange / replacement. You can also call Lionel directly.
George