Channel balance replacement

A handy person from Bradenton,Florida says:
I have a sash guide that does not match exactly your pictures. The metal U shaped channel is 30 inches long and 9/16 inch wide, 5/8 inch deep. The window is 6 yrs. old. I believe the manufacturer is Norandex, could also be Alcoa. There are no numbers stamped on the metal,however there are painted numbers and letters. I have another similar window that has a 2940 code stamped on it. If you don't have an identical match do you have a substitute?
A customer submitted photo of channel balance attachments.
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Donna from SWISCO responded:
You might need a pair of S380-30 with stamp 2940, to check, please remove the window sash and place it on a scale.
We need the weight of the window sash in pounds to determine the proper stamp option.

A 30" Series 380 with stamp option 2940 will carry a window sash weight range of 23 through and including 28 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.
A handy person from Bradenton,Florida says:
Thanks for your help. I weighed the window sash and because of double glass it weighs 36 lbs. Would I need a 2950 0r 2960?
Profile picture of Donna
Donna from SWISCO responded:
Thank you for the information. That is certainly a heavy sash! In this case, you will need a S380-30 with the 2965 option; this will carry a window sash weight range of 35 through, and including, 39 pounds.
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