840 S190 COIL BALANCE SPRING too loose for my window

A quick learner from MD says:
February 14, 2020
I bought replacement 840 S190 COIL BALANCE SPRING.
But my window is still too loose.
Can I use other coil spring to make my window tighter?
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Casey from SWISCO responded:
February 14, 2020

Hello,

Individually, this coil balance with an 840 stamp can hold 8 pounds. That means that if you have one coil on each side of the window, it will support a 16-pound window sash. If your window weighs more than 16-pounds, that would explain why your window is still sagging. Could you weigh the window sash and get back to us so that we can get to the bottom of this for you? Thank you!
A quick learner from MD says:
February 16, 2020
Thank you Casey.
One of the window is 19 pounds. Another window is 19.4 pounds,

But the original springs have stamps of 840.

Should I change springs?
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Casey from SWISCO responded:
February 17, 2020

For your sash weights, I'd suggest using an S190-940 coil spring on each side of the window. The added strength will provide extra support to keep your sash raised. Thank you. 
840 S190 Coil Balance Spring
840 S190 Coil Balance Spring
S190-840
$11.32
940 S190 Coil Balance Spring
940 S190 Coil Balance Spring
S190-940
$11.94
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