Sash Balance replacement

A home owner from Duluth, MN says:
August 3, 2020
Hi, I have double hung Andersen windows, around 1962. Looking for replacement for one that is stamped "6 31" with a smaller "32" in the corner. I think I know which one you'll say (24-637) but it looks like it attaches differently than the original. (Original: a screw in the middle of balancer vs New: two screws at the end of the balancer.) I hope the replacement will work. Thanks.
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Tom from SWISCO responded:
August 6, 2020

The newer version 24-637 does attach differently than yours, but it is unfortunately your only option. You probably won't find the old version anywhere. You'll have to make a notch in your window frame in order to install our balance. 

The diagram below may be of some assistance.

User submitted image of their window hardware.
A home owner from Duluth, MN says:
August 6, 2020
I already bought a new chisel! Thanks. I can't see the diagram you attached for some reason. I bought two 637s and will see how it goes with the first window of the three I need to fix.
Andersen Sash Balance, 623, 627, 631, 637
Andersen Sash Balance, 623, 627, 631, 637
24-637
$54.20
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