Nuair Window Channel Balance replacement needed

A quick learner from Palm Harbor, FL says:
Hi: I need to replace a Nuair window balance that appears to be your part # S380-35. There are no stamping in the balance frame just the markings - 34 9 DX CMC 2. It is from a single hung non tilt Nuair window and the metal channel is 35" long and 9/16" wide. Please confirm the correct replacement part #. See images attached.
A customer submitted photo of channel balance attachments.
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Tom from SWISCO responded:
Thanks for posting. Can you please tell us the weight of your sash? This will help us determine the appropriate stamp option.
A quick learner from Palm Harbor, FL says:
The sash weighs 31.6 lbs
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Donna from SWISCO responded:
35" Series 380 with stamp option 3450 will carry a window sash weight range of 30 through and including 34 pounds.

This information is based on 2 balances per sash. Balances are designed assuming friction in the jamb weather-strip will carry a portion of the sash weight. Suggested sash weights are approximate.
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