Need to replace broken part of BSI Window

I have a broken part that is connected to the actual window (I have included two pictures each of the broken part and what a non-broken part looks like). The broken part fits into window balance allowing the window to stay up.

I have also included a picture of the guide on the frame the window fits into showing that it is a "33H" BSI Window - it's the only marking on the entire window and frame.

Thanks for your help!

That was it! I went ahead an ordered two.

Thank you!