Channel balance replacement

A quick learner from Hutchinson KS says:
I have a channel balance with a broken sparing and need replacement for it. The channel is marked or stamped 1620 and is on an Alcoa Window. The aluminum channel is 15 inches long with nylon ends. It looks like the S350 with what I could tell from the Photograph. The House was built in 1980 with double pane insulated windows. Replacement seals came from ALCOA Stolie plant in Sidney Ohio. I have research it and the window and exterior divisions were sold to ply gem.
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Paul from SWISCO responded:

I agree,  our Series 350 balance system looks like the best match for your Alcoa window. The channel length is puzzling, though. For stamp option of 1620, the metal channel length should be 17", not 15". Can you confirm both details? A 15" balance should have a 1420 option, for example. 

A quick learner from Hutchinson KS says:
The overall length would be 17. I read the metal only was used to signify the length. That wording caused me to use the 15 length. I hope that clears that up.
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Tom from SWISCO responded:

You're correct, the metal channel should be the only thing you measure. Your metal channel should be 17" long, based on your stamp. I would double check just to be sure. Those nylon attachments shouldn't add a whole 2" to length.

If you are confident your metal channel is only 15" long, then our S350-15 will work for you. You'll just have to weigh your sash on a scale and refer to the chart shown on the S350-15 store page to confirm the best stamp option.

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