Balance Spring for CertainTeed double hung window

A quick learner from Hawaii says:
I have 3 ea, 4040 double hung, Newcastle Series, Dual Glaze Low-E Clear Glass windows. Purchased in 2006. Had been receiving replacement balance springs SA336 for springs that continually break. (They have stopped replacing springs.) One window (replaced due to moisture) weighs 22.8 lbs. The other windows weigh 19 lbs.
All windows cannot stay open/closed. What do you recommend?
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Bob from SWISCO responded:

Thanks for writing in. I'm fairly confident we can replace this balance system for you, but I want to be safe and confirm we know what components we're working with. Can you show us pictures of the pivot shoes that the coil balances attach to? The identity of the pivot shoe determines the Series of coil balance needed. From there, we'll work out what you need for each window. Many thanks.

A quick learner from Hawaii says:
Photos attached
Thumbnail of the uploaded file named A6B20A27-9C6A-42D2-9E88-AEEE75F55904.jpeg
Thumbnail of the uploaded file named SA 336 stamp
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Bob from SWISCO responded:

Thanks for getting back to me; perfect, this is exactly what I needed. Your pivot shoe looks like our 15-192. This is compatible with our Series 170 and Series 171 Coil Balances. If you need just one coil spring on each side of the sash, then you'll only need the Series 170. Specifically, your stamp code suggests you need the S170-336, which is meant to hold 6 lbs of weight individually. Let me know if you have any other questions.

A quick learner from Hawaii says:
The S170-336 cannot support the weight of the windows. One window weighs 22.8 lbs. The other windows weigh 19 lbs.
What do you recommend?
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Bob from SWISCO responded:

In that case, you're going to have to divide the weight between multiple different springs. Specifically, you'll need two on each side.

I recommend using our S170-406 (6 pounds) and S171-405 (5 pounds) on each side of the sash. These four springs should add up to 22 pounds of support. You want to install the S170-406 on the bottom and the S171-405 on top. You'll also need a second 15-156 cover for support, as well as another 15-157 bushing.

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