The metal track is 26"x 9/16" and it has 2520 stamped on it. The metal pulley where the spring connects is broke. I figured I would replace the whole piece.
Paul from SWISCO responded:
October 12, 2017
Thanks for sending us your question and photos. It looks like you need our-370-26 side load channel balance with a spring weight option of 2520. Let us know if that will work for you.