Need a window channel balance replacement but need help determining size

A quick learner from Oakland, CA says:
I have a 33 inch window balance (1/2 inch width inside) that I need to replace - I would need at least four of these window channel balances. Attached are pictures showing the markings, and the top and bottom notches.
User submitted photos of a window balance.
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Paul from SWISCO responded:
Thanks for posting. Please see our S385-33 channel balance. I believe this is a good match. As for the proper option, I recommend weighing your sash on a scale to determine what would be best. You can refer to the chart we have on the S385-33 store page.
A quick learner from Oakland CA says:
Paul: Thanks for your help. It is hard for me to weigh the sash -- I tried putting a bathroom scale underneath the window while it is still installed but it appears that i need to take the window out altogether to get an appropriate weight -- something that I just don't have the capacity to do. Is there a way I can mail a sample of the window balance so an appropriate match can be made.
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Paul from SWISCO responded:
Unfortunately, being sent a sample of the balance will not allow us to determine the spring strength. The only way to know for sure is for you to weigh your sash. If you are unable to do so, you could possibly go with our 3265. Two balances with the 3265 option can hold a sash weight of 35 through 39 pounds, but this is just an educated guess. I cannot guarantee that it will work for you.

Removing the sash from the window frame is actually very simple. Check out this video, this should give you some idea on what you can do.
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