Wondow
Hello there!
Thanks for reaching out to us. We're happy to help with this. Could we see close-up photos of the top and bottom fittings? Can you show us a photo of the inside of the balance's metal channel where the innerspring connects to the pulley mechanism? That'd be located in the middle of the channel. Can you also measure the bottom shoe as shown below and tell us what you find?
The tape measure obscures much of the top fitting so it's hard to say whether it has wings or not. Can you confirm? We still need to see the spring connection inside of the metal channel as well as the confirmed shoe depth.
We have the S380-21 and S385-21 channel balances but I can't confirm if these will work for you without seeing the spring connection point. With that said, the difference between these two balances is the depth of the bottom shoe as shown below.
You will also have to weigh the window sash on a scale to determine the proper stamp option since your old stamp is from an older rating system. There's a chart under the product description on the S380-21 and S385-21 store pages that you can use as a reference.
