Certainteed 36 x 58 vinyl double hung window balance "#86170"

A home owner from Gorham, Maine says:
October 10, 2023
1997 house with Certainteed vinyl DH windows 36x58, typical. Lower sash of one needs both balances. See attached photo - pulley appears to have "Certainteed 86710" imprint on one side.
Please let me know if I can order these spring balances, or if you need more information.
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Lauren from SWISCO responded:
October 11, 2023

Hello, thank you for posting,

Your balance assembly resembles the 15-192 pivot shoe that is compatible with the Series 170 and Series 171 coil springs. Please review the dimensions to confirm a good fit! 

detail of 15-192
detail of 15-192

To choose the correct coil weight, review the original coil for a number stamp into the metal. If there is no marking, please provide the weight of the sash to move forward. Thank you!
A home owner from Gorham, Maine says:
October 12, 2023
I recently posted and received a reply that my balances are 15-192 pivot shoes. The coil spring appears to have "381" or "3S1" stamped below "SK". Very faint.
Do these numbers correspond to any standard coil spring nomenclature?
I'd like to order one pair, maybe two pairs, for the next one to fail.
Please see what you think, and help me to set up an order.
(I did check the dimensions - definitely the 15-192.)
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Lauren from SWISCO responded:
October 12, 2023

The stamp does not directly translate. To move forward are you able to provide the weight of the sash? The sash will need to be removed and placed on a scale. Thank you! 
A home owner from Gorham, Maine says:
October 18, 2023
sash weighs 16 to 17 pounds.
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Lauren from SWISCO responded:
October 18, 2023

Thank you,

I recommend using (1) S170-408 coil spring on each side of the window. Both coils together will support a 16 pound window. Even if the weight is closer to 17 pounds as long as the weighted coils are within a pound range, they will be fine.

If you need a new cover, take a look and compare the 15-156 or the 15-185 cover with the 15-157 balance drum. 

Please let me know if you have any additional questions! 
408 Series 170 Coiled Balance Spring
408 Series 170 Coiled Balance Spring
S170-408
$6.55
CertainTeed Pivot Shoe
CertainTeed Pivot Shoe
15-192
$6.39
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