Channel replacement part

Thanks for posting. I believe we'll be able to help, but we will need more information. First, can you re-measure the length of the metal channel? Be sure not to include the nylon attachments on either end in this measurement. Second, please give us the exact weight of the window sash. Using a bathroom scale to obtain this should suffice. That will tell us what stamp option your balance needs--the stamp indicates the strength of the balance. Finally, please compare the depth, or 'heel-to-toe' measurement, of your balance's bottom attachment or shoe. It should be one of the two possibilities below.

Comparison of the S378, S380 and S385 balance shoes.