I'm not sure what you have, unfortunately. There are dozens of different balances with that stamp. It's not a product code or anything, it just indicates the strength of the spring.
In order to figure out what Series this is, I need you to remove an undamaged version of this balance from the window and show me clear pictures of the top and bottom nylon fittings. I will also need to know the dimensions of these fittings.
Thank you,
I apologize for the inconvenience, but we will need to see one more picture based on the style of balance that is shown. Can we see a picture of the inside of the metal channel where the spring and pulley system connect? From there we can determine the best fit. Thank you!
Thank you,
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.
For a 35" 40 pound sash, you would need a 3465 stamp option. I recommend making sure the weight is exactly 40 pounds as the weight ranges only differ by a few pounds. Please see the chart below and let me know if you have any additional questions.