6 or 9? Coil Balance Help

A handy person from new york says:

its definitely a half inch coil balance. the only stamp on it i see is pictured. dont know if its a 9 or a 6.. can you tell?I have a double support detent clip and the color looks the same as a 9 so my guess would be 9 but please let me know your thoughts. ty!

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Bob from SWISCO responded:

Unfortunately this is always tricky. There's really no way of knowing whether it's a 6 or 9. Ultimately you'll need to obtain the exact window sash weight. Give us that exact weight, and show us pictures of the pivot shoe that these coils attach to, and we can work out what you need. 

A handy person from new york says:

so here is a pic of the full assembly and another pic of the coil. the coil does have a stamp on it and its either a 6 or a nine depending on which way you hold it. the way I am holding it in the pic its a 6 but upside down its a 9. What do you think? i think its 6 because upside down it looks like a g.

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Bob from SWISCO responded:

Based on these photos, looks like you have a 15-180 Pivot Shoe, which uses Series 190 Coil Balances. So this spring would either be a S190-640 6 lb spring, or a S190-940 9 lb spring. Unfortunately I am not confident enough to say either--coil spring stamps are often not too reliable, nor consistent in how they are printed. So I don't think we can go off the stamp's appearance alone. I'm afraid there's really no way around having to obtain the exact window sash weight. Removing the sash and gently placing it onto a bathroom scale should do the trick. From there I should be able to tell you exactly what you need. 

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