Kolbe double hung window balance replacement

A home owner from Waukesha, WI says:
need to replace several block & tackel balances, but will order 1 to see if fit is exact before I order out what I need. window is Kolbe double hung insulated glass W 26" H 19.5 weight 16.5#. problem spring brakes at upper attachment where first wind begins with uppwards force of spring goes up it tears hole in alum where long rivet secures spring.. thus replacing spring is not possible.

I think your ribbed channel 17" series 751 with shoe 15-014 black is what I need Option 16HD. channel is 17", 9/16 w, 5/8h stamped 16HD spring attaches to rivet 2 1/4" from top Long S clip attaches 13/16" from top. bottom shoe attaches 1/2" from bottom on alum rivet see photo

bob b.
User submitted photos of their ribbed channel balances.
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Paul from SWISCO responded:
Good morning, Bob. Thank you for your patience.

From the photos you've submitted, it appears you have the Series 751 Channel Balance. The Series is determined by the attachment combination, yours being the 15-014 and the 19-030.

The stamp #16.5 is normally translated to the 16R stamp for the Series 751 Channel Balance. However, if the original manufacturer used the 16HD stamp, you can go ahead and use the 16HD for the Swisco balance replacement.

Please be sure to double-check the markings on your channel.
How to install a ribbed tilt channel balance with knife lock shoe
How to install a ribbed tilt channel balance with knife lock shoe
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