need help with channel balance stamp translation

A contractor from Walnut Creek says:
Hi again,

I have a couple of windows with 1/2" non-tilt channel balances that have failed. I've identified the replacement as your Series 390 balances with the 19-001 top and 15-001 shoe. One balance is stamped "1930 BSI" which seems obvious enough--it's 20" long so I will order the 1930 option.

The other balance is stamped "3190 BSI 32" which doesn't seem to fit in your option list. The channel is 32" long, the vinyl sash it's supporting is 41" x 31" (glass size, or DLO). What would your recommend for the strength of this balance?
User submitted a photo of a window balance.
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Tom from SWISCO responded:
I'm not sure! You will have to remove the sash and place it on a scale to determine its weight. Then, you can compare that weight to the option strengths we have listed under the S390-32.
A contractor from Walnut Creek says:
The sash weighs 35 pounds...right at the upper limit of option 3160. Should I go with this, or option 3265 (no weight range listed on the page...)?
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Tom from SWISCO responded:
Yes, I think that would be a good idea! Two balances with the 3265 stamp option can carry a window sash weight range of 35 through 39 pounds.
A contractor from Walnut Creek says:
Thanks Tom. I may wind up ordering both the -60 and -65 just to make sure.
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