Caldwell Balancer marked 33-4 ES. 34" long, 1/2" wide

Thanks for posting! This window balance is similar to a few different series we supply. To narrow down the correct option(s), I'll need to see a photo of the spring inside the channel balance. I'm particularly looking to see a photo of the bracket connecting the spring and the cord (string) in the middle of the channel.

Please let me know if you have any questions!

Thanks for the additional photos. Your window balances can be replaced with either the S380-34 or the S385-34. To determine which of these is the correct replacement, you'll need to measure the depth of the bottom shoe.

Our 3340 stamp will support a sash weighing between 23 to 28lbs.

Comparison of the S378, S380 and S385 balance shoes.