Hello there! Thanks for reaching out to us. We can help with this but it must be a custom order due to the configuration. The metal channel should end in 5/8" though. For example, if the stamp is 25-5, the metal channel would measure 25-5/8" long. Custom orders are nonrefundable so we recommend double-checking to be sure.
Speaking of stamps, there should be one printed on the metal channel before "BSI". Can you confirm? You can also check the balance on the other side of the window for an intact stamp.
Thanks for confirming! We still need to know the stamp on the metal channel to get the ball rolling. If the stamp is too faded, we will need to know the exact weight of the window sash.
The stamp we're looking for has 3 numbers before the "BSI" but it sounds like yours is faded. In that case, we will need to know the exact sash weight to get this moving for you. That will allow us to determine the proper stamp for your replacements.