New window balance
Hello,
With this combination of attachments, you could have either the S380-24 or S385-24 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.
You'll also need to locate the stamp code on the metal channel to choose the corresponding spring strength options for your replacement balances. Thank you and let us know if you have any other questions or concerns.
The 23-9 is the strength code but, unfortunately, it is from an outdated system that is no longer used. I would recommend weighing your window sash and following the chart shown under the S380-24 product description to choose the corresponding strength option.