Gino's right on the money (He's practically part of the Tamiya family now, Congrats again.).
The link will give you a 1-800 number to Tamiya in CA, PST mon-fri 9-6. With the part # you can get almost anything currently in production. Beware, your going to pay a little for it. If there's a problem with the existing tracks and the kit is recent, they might hook you up, it's worth a shot.