Replacing two (2) window balance channels

A quick learner from Lakeville, MN says:
December 23, 2023
The balance channel has the numbers 2740 imprinted vertically on the back of the channel. Then BS1 or BSI below the zero of the numbers imprinted horizontally. The channel is 28 inches long and 1/2 inch wide. Let me know if you need more photos. Thank you!! Julia Harding
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Bob from SWISCO responded:
December 23, 2023

Hi Julia. This looks like either an S351-28 or S390-28. The only difference between these two channel balances is the depth of the bottom nylon shoe, or the measurement from 'heel' to 'toe'. See the illustration below for reference. Compare both with your old balance to see which matches best. Make sure you use the balance that has an undamaged shoe to measure this. In either case, choose 2740 as a stamp option. Let us know if you have further questions.

Comparison of the S351 and S390 balance shoes.
Comparison of the S351 and S390 balance shoes.
A quick learner from Lakeville, MN says:
December 24, 2023
Thanks so much!! I ordered the one that does appear to match. I'll let you know if it is right. Merry Christmas!!!
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Bob from SWISCO responded:
December 24, 2023

Sounds good, Julia. Let us know how you make out, and Merry Christmas to you as well! 
28" Series 351 Channel Balance
28" Series 351 Channel Balance
S351-28
$10.97
28" Series 390 Channel Balance
28" Series 390 Channel Balance
S390-28
$10.97
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