29G op BSI sash balance

Thanks for writing. This looks like a Series 770 Channel Balance. However, this will likely need to be specially made due to the extra-strong spring strength and the weight of your window sash. Could you confirm for us the length of the metal channel? In the time being my colleagues and I will look this over and get back to you if we need any more information. Many thanks.

Thanks for your patience during this busy season, Frederick. In general we never recommend trying to repair individual balances; this can actually be dangerous when it comes to the spring mechanism, as it is under a lot of tension. But in general, these balances are built as a singular component, and when they break its time to replace them wholesale. 

The good news is that we've added the stamp option of 29G for the S770-29 online. It will take 6 weeks for these to be made up, but you can sign up to be notified the moment its available through the S770-29 product page. Let me know if you have any other questions.

I feel pretty confident that our S770-29 is the right balance for you, yes. The only thing you may want to double check is how it installs at the top of the window frame; ours uses a screw, but if yours uses some other method then let me know.