Hello,
We'd be happy to look into this for you but we'll need a bit more information to narrow down your options. If you could show us the connecting point between the spring and pulley inside the metal channel, That will help us confirm if our stock balances could work for your repair or if they would need to be special ordered. Thank you!
Thanks for getting back to us. Based on your photos, you could have either the S380-21 or S385-21 channel balance. You’ll need to measure as shown below. The Series 380 has a 1" bottom attachment, and the Series 385 has a 1-3/32" attachment.
Your stamp code would generally correspond to 2030 strength options for your replacements but they would be calibrated to support a sash between 12-15 lb. Note that both balances need to be calibrated to support the full weight of the sash. There is a chart on the product page that explains how to choose your option. Just let us know if you have any other questions or concerns.
That's great! We appreciate your business and we'll be here if you need anything else.