Gerkin single hung 6100 series

Before we can recommend a replacement balance, we need for you to remove the balance completely from the window and upload images of the entire balance. From there, we can get back to you with more information.

To expand on Paul's response, it looks like you want to replace the pulley system in your balance. This cannot be replaced by itself. Once it has broken, you need a new balance. We can supply a new balance, but we'll need more detailed photos, like Paul outlined. Thank you!