Hello,
Your channel balances resembles the S770, which attaches to the top of the window with a screw and anchors to the pivot shoe with a terminal clip at the end of the pulley cord.
If the pivot shoe is the part that broke, I would recommend removing yours from the window to compare to the 15-129 shown below. Take a look and thanks for posting!
We do offer a 19B strength option for the S770-19 channel balance, which is also referred to as a block and tackle balance in the industry. The 15-129 is often used with the S770 but we would need to see your pivot shoe uninstalled, along with written-out dimensions, to confirm if a closer match is available.
