replacement channel balances

A home owner from RIGBY,IDAHO says:
March 19, 2012
was going to order channel balance top 19-005 and bottom 15-004 20"..was given mandatory option numbers of 1910 through 1940 with no explanation..not sure which to choose..also old channel balance does not have a stamped number on it...only writing on old balance is 20 3 GW CMC 11..PLEASE ADVISE WHICH ONE TO ORDER
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Paul from SWISCO responded:
March 20, 2012
Thanks for posting. The stamp on your balance determines the weight that your balances can support, 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.

Can you confirm the length of your metal channel, however? Based on your stamp, it seems like your balance should be 21" long, not 20". Please let me know.
A home owner from RIGBY,IDAHO says:
March 20, 2012
The aluminum (silver) part is 20 inches not counting the end pieces
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Paul from SWISCO responded:
March 20, 2012
Thank you. In that case, we will need to know the weight of your sash in order to determine the best stamp option for you. To do so, simply remove the sash from the window and place it on a scale.

To see how to remove your sash, please take a look at our video tutorial on how to replace your tilt window channel balance.
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