Hello, thank you for posting,
We should be able to help, but unfortunately only one of the pictures came through. Are you able to resubmit the others for us to get a closer look at the balance needed? Thank you!
Thank you for the additional pictures,
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.
The length of the metal channel excluding the nylon attachments should measure 28" long and you will need a 2730 stamp option. Please review and let me know if you have any additional questions.
It appears that you are in need of a new top sash guide. Please review the dimensions of the 18-202 style below to confirm a good fit! Let us know what you think!