43# window
Hello,
Could you show us a photo of one of the balances, including both top and bottom attachments, from an identical but slightly smaller window? That should at least confirm the correct series of balance that you should be using and then we can calculate the spring calibration based on the sash weight you've provided.
Great! With this combination of attachments, you could have either an S380 or S385 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. Once we determine the correct replacement, we can work on determining the correct calibration to support your window sash.
Perfect. I just sent over a custom order link and price quote for two balances that will support a sash between 42 and 45 pounds. Take a look and please let us know if you have any other questions. Thank you!