atrium replacement part question

A home owner from Arizona says:
I want to order replacement channel S390-29 but I'm not sure how to determine sash weight range. There is no stamp on my existing 29" channel balance. Printed on back of channel is "28 3 AX GMC 7". Could I weigh the moveable window and use that weight to pick the stamp option? Thanks in advance for any help.

Tom Dopplick
Profile picture of Tom
Tom from SWISCO responded:
28 3 is actually the stamp you need to consider. I would recommend 2830 based on it, but you could always weigh your sash to confirm. That's the most accurate method.
Reply to Thread
Use this form to ask a follow-up question or to share your experience regarding this subject.
(your email address will be kept private and is only used to inform you when a response has been made)