Gilkey Double Hung Vinyl Windows -coil spring

A home owner from Buffalo Grove, IL says:
I am fairly certain these two parts are correct (based on patent 5,353,548)
Coil Housing Pivot (plastic) 15-087
Tandem Coil Housing (plastic) 15-086
There was no number on the coil spring. Need help in finding the correct coil spring
The spring is 1/2" wide with two round holes
Dimensions of the combo Coil Housing Pivot and Tandem Coil Housing
4" x 1 and 1/8" x 1/2 "
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Casey from SWISCO responded:

Hello,

I agree that your assembly appears to match the 15-087 and 15-086. These parts are compatible with the 15/32" wide S180 coil springs. 

To confirm the correct strength option for your coils, you would need to remove and weigh the window sash that these balances support and divide the weight by the number of coils used on both sides of the sash. Thank you!

A home owner from Buffalo Grove, IL says:
Thank you for the info. I will do that and get back to you.
A home owner from Buffalo Grove, IL says:
Sash weighs 21 pounds. There are 4 coil springs, two on each side. 21/4=5.25. Let me know what spring I need to order. Thank you very much.
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Casey from SWISCO responded:

I would recommend using one S180-5 and S180-6 on each side of the window to support a 21-pound sash.

A home owner from Buffalo Grove, IL says:
Thank you for the info. I will be placing my order. One more question. Can you please tell me if the two springs lined up with the two holes hook onto the mounting bracket (part # 16-024) together?
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Casey from SWISCO responded:

Correct, the coils attach to the top mounting bracket as shown in the diagram below. 

Series 180 coil balance diagram
Series 180 coil balance diagram

A home owner from Buffalo Grove, IL says:
Thank you very much for your assistance.
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