seeking replacement spring balance for single hung sash windows

A quick learner from Tucson AZ says:
April 17, 2021
The existing spring balances still function but have become sticky. Lubrication has helped but not resolved. Planning to replace two pairs now and the remaining four pairs later. Please help to ID the correct model number.

Window manufacturer: Atrium
Year installed:2004
Markings: "28 3 CX CMC 7"
Length of metal portion: 29" (as shown in attached photos)
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Casey from SWISCO responded:
April 23, 2021

Hello,

Take a look and compare our S395-29 channel balance with a 2830 strength option to your original assembly. Thanks for posting! 
29" Series 395 Channel Balance
29" Series 395 Channel Balance
S395-29
$10.87
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