replace broken channel balance

A home owner from Moorpark, California says:
I have a broken channel balance, the cord snapped, also the pin holding the spring broke.

The housing is 34", the marking is 3330, which I believe means a 34" balance supporting 30 pounds weight.

The other balance (which is not broken) is marked 3320. Does that mean it's a 20 pound balance? Or or there left/right balances? They appear to be interchangeable.

The window sash weighs 16 pounds.
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A home owner from Moorpark, California says:
Since my sash is 16 pounds, do I need only a 20 pound balance?

Is a 20 pound balance easier to operate than a 30 pound balance?
A home owner from Moorpark, California says:
I also have another broken channel balance to replace, this one looks the same on the ends as the 3330 as shown in the attached pics, but is marked 2730, the housing is 28" long. The other balance in this window is a 2720, it is not broken.
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Casey from SWISCO responded:

Hello,

Take a look and compare our S350 channel balance to yours. The strength codes on your balance are part of a weight system but don't indicate the exact weight of the window. For example, the S350-34 channel balance with a 3330 strength option would support a sash weight between 18 and 23 lbs. You can find a chart under the product description of each balance with the weight ranges for each of your stamp codes for the corresponding balance length. Thank you!

A home owner from Moorpark, California says:
Thanks so much, the replacement channels were a perfect fit, and easy to install. Your parts locator is a great service!
S350-28 : 28
28" Series 350 Channel Balance
S350-28
$10.25
VIEW >
S350-34 : 34
34" Series 350 Channel Balance
S350-34
$11.28
VIEW >
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