Stronger 28" 770 balance

A quick learner from Dayton, Ohio says:
I ordered parts for several windows and was successful replacing all the parts. Everything worked but one of the windows must be too heavy. The 28" 770 (28B) balance wasn't strong enough to hold the window up.

The actual size of the window the balance operates is 41 1/2" wide by 29 3/4" tall. The other windows are the same height but are only 29 1/2" wide and they operate fine with the new balances I ordered. I do not have a picture but the original balance looks relatively the same as the replacements I ordered.

On the original balance the stamp reads 27DS 35. Do you have a stronger balance in the same length that will operate this window?
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Paul from SWISCO responded:
Thank you for posting. Before we can offer an applicable replacement balance, can you first give me the weight of your sash?
A quick learner from Dayton, Ohio says:
It weighs approximately 34 pounds.
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Paul from SWISCO responded:
For a S770-28, the stamp option of 28F will carry a sash weight range of 32 through 36 lbs. Do you think this may work better for you?

Please keep in mind that this information is based on 2 balances per sash. Balances are designed assuming friction in the jamb weather-strip will carry a portion of the sash weight. Suggested sash weights are approximate.
A quick learner says:
yes I do. Thanks, I will place an order.
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