My coil balance will not let my windows won't stay up

A home owner says:
Hi,
I have a Certainteed windows the part above broke, I ordered from your website part number S170-263 coiled balance spring my husband installed it still not staying up, what is your suggestion. The picture of the coil I have uploaded says on it number 10. Thank you
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Paul from SWISCO responded:

We are sorry to hear the trouble you had with your coil springs. Let's see if we can help. Could you weigh your window sash and get back to us with that weight number? 

A home owner says:
Hi,
My window sash weigh is 32LB
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Tom from SWISCO responded:

Wow, that's pretty heavy. The S170-263 can only hold 3 pounds per spring. Using only one on each side gives you only 6 pounds of support, which obviously can't hold up 32 pounds.

However your old springs appear to be too weak, as well. With a stamp of 10, that indicates to me that having one on each side would only give you 20 pounds of support, which still isn't enough. Did you ever find that they were too weak?

Can you confirm the exact weight of your sash? Could it be more like 20 pounds?

A home owner says:
Hi,
My husband did the weight again so the window is weight 17 pounds. It was a mistake for the 32 pounds. Thank you

Theresa
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Tom from SWISCO responded:

Thank you, Theresa! I thought that might be the case. With that sash weight in mind, I recommend using one S170-409 spring on each side of the window. I think this will be sufficient for your sash weight.

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