Window balance springs

A quick learner says:
October 2, 2023
I have a house of Pella vinyl windows I installed. From day one, some of the windows wouldn't stay up in sections of their tracks. I took a look at the shoes and springs and the windows that won't hold seem to develop gaps in the springs.

On one window I removed the shoes and springs, cleaned the springs, rewound them to get rid of the gaps and reinstalled them. The windows were unchanged and the gaps returned. I then thought the gaps were forming because the springs were sticking so I put a little WD-40 on them and it improved the situation.
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A quick learner from Columbia, MD says:
October 2, 2023
I checked the windows that won't stay up and they all have gaps in their springs.

All of the ones that do stay up have NO gaps in their springs.

The question is, is the problem the springs or the shoes or both?
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Lauren from SWISCO responded:
October 4, 2023

Hello, thank you for posting,

It sounds like the coil springs are worn or damaged. I would recommend removing the full assembly to see if there is any visible damage to the pivot shoe as well.

Please start by reviewing the style style and dimensions of the 15-251 inverted universal single support along with the S160-10 coil spring. This spring can support 10 pounds of weight. Together with the other side, the total window sash weight should be 20 pounds, please compare. 

Measurements of 15-251
Measurements of 15-251
Inverted Universal Single Support
Inverted Universal Single Support
15-251
$3.97
10 lbs Series 160 Coil Balance
10 lbs Series 160 Coil Balance
S160-10
$6.34
Mounting Clip
Mounting Clip
16-032
$0.90
Mounting Bracket
Mounting Bracket
16-031
$0.90
How to replace a window coil balance
How to replace a window coil balance
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