How do I determine the window sash weight

A home owner from USA says:

July 8, 2015

I have the part number 34C BS1 which translates to Series 765 Balance, product code S765. I need a 35 inch replacement so S765-35. The balance in the window does not have a sash weight stamp. The window is large, 35 Inches by 32 1/2 for the bottom pane. How do I know what weight option I need. Do I have to weigh the window???? They are double pane, single hung new construction windows from 2004. I am guessing Anderson brand, but not sure. Would like to get this done ASAP as home is being sold the end of the month. second question: how long will it take to get the part? Thanks for the help.

Tom from SWISCO responded:

July 8, 2015

Yes, if your balances do not have any stamps then the only way to determine what stamp option you need is to place the sash on a scale and compare it to the chart we show on the S765-35 store page.

As for how long it will take, we offer several shipping methods to choose from, so it will depend on what you choose.

35" Series 765 Balance

S765-35

$15.34

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