this is the piece that sits on the window sash and slides into the track

Thanks for writing in! Your balance shoe looks similar to our 15-195B 1-/4" T-Lock Balance Shoe but I suspect you may have a balance with a grove at the end of the channel where this shoe installs. If so, this shoe will not be compatible with your existing channel.

May I please see a photo of the balance?

Please don't hesitate to reach out with any questions.