Coiled Balance Spring S170-403

A quick learner says:
I'm looking for S170-403 but I can't find it.
Is S170-405 okay to replace 403?
Please let me know.
Thank you.

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Tom from SWISCO responded:

No, I believe that would be too strong. Please give us a little more time to look into this. We may be able to find a spring  that can work for you. In the meantime, if you could tell me the weight of your sash, that would be a huge help.

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Tom from SWISCO responded:

Thanks again for waiting. We unfortunately weren't able to acquire a 3 pound spring in your size. The only version we found had a 26" long spring compared to your 40" spring. See our S170-263. This spring is much shorter than yours and depending on how tall the window is you may not be able to close it.

If that's too short, then your only other option would be to go with the 5 pound S170-405 after all. I still fear that it may be too strong, but it is the weakest spring we carry in this style and size. You may find the window harder to close and, in a worst case scenario, it may even drift up after you close it. I cannot be sure. 

I'm sorry that we cannot offer you a better match.

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