Window sash balance identified on part as 2730 A length of part is 28"
Hello, thank you for posting,
Your balance resembles the S350-28 channel balance with a 2730 stamp option. The depth of the bottom shoe is 1-3/32. Please compare to confirm a good fit and let me know if the measurement is different.
Let us know if you have any additional questions.
The length of the spring in the metal channel does not matter when it comes to replacements. You just want to make sure the spring strength will support the window sash. Your original balance is stamped with 2730 which indicates the window sash weighs between 13 to 19 lb pounds. If you have any uncertainty that is incorrect, I recommend weighing the sash to confirm.
Let me know if you have any additional questions!