Window channel balances

A handy person from MA says:
I'm replacing the channel balances in several double-hung windows. It seems odd that the channel balance for the upper sash is the same as the lower sash because the lower sash stretches the spring so much more. The part number stamped on each is W 28HD and is for a tilt window. If I replace all four balances in a window, do I order the same part for all four? Or is there a different part for the top and bottom?
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Paul from SWISCO responded:
Good Morning,

Yes, you will order the same balance for all four.

Giving us the stamp on your balance is a good start. To continue with the rest of your research, please upload a few photos of your channel balance(s) so we can take a look. Be sure to include photos of your balance attachments (shoes) and the length of the channel portion of your balance (not including the attachments).
A quick learner from MA says:
Thanks for the reply. I've uploaded a picture of the shoe and the channel. There are no other markings other than "W 28HD". The aluminum channel is 29 inches long. Could you suggest a part number?


User submitted photo of channel balance attachment.
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Mike from SWISCO responded:
Hey George,

This looks like our 15-014 Balance knife lock shoe, which is used with the Swisco S751 Channel balance. The last link will take you to the 29" balance, where you'd select the option "28HD".
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