Window spring and rail thingy

A quick learner from Glenview Illinois says:
Sorry about the description, but not sure on the names.
User submitted a photo of a window balance.
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Paul from SWISCO responded:
The pivot bar resembles our 26-021, while the balance looks like our Series 770 channel balance. Check them out and let me know if you agree.
A quick learner says:
the 770 balance looks close, but the issue is that the top, when attaching to the window, is not with a screw, but with a metal hook that slips into a cut which is part of the frame.

Help is appreciated, thank you
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Paul from SWISCO responded:
Thank you for getting back to us. Hmm... if that's how your balance is attached, then you might have something different than I originally guessed. Could I see a more detailed picture of the balance's metal channel? I'd like to see the outside of it, rather than the inside which you have pictured above. Thanks.
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