Milgard window glide
Hello, thank you for posting,
We can assist with a replacement balance, but to further review, are you able to provide a closer image of the inside of the metal channel where we can see the attachment at the end of the spring? From there we can narrow down the correct series for your window.
Please also double check the length of the metal channel excluding the nylon attachments. Based on the stamp, it should measure 27 inches long. Thank you!
I apologize for the inconvenience, what we need to see is a closer image of the inside of the part shown below.

Great thank you,
With this combination of attachments, you could have either an S378, S380 or S385 channel balance. You’ll need to measure as shown below. The main difference is the depth of the bottom shoe. Please compare to determine the right fit.
You will need a 27" balance with a 2640 stamp option. Let me know if you have any additional questions.