Caldwell Sash Balance Identification

A home owner from Florida says:
Hi, I need to replace the channel balances on a window, specifics are:

1/2 inch channel
29 inch long

Photos of the end caps attached.

Believe the top is 19-002 but can't tell if the bottom is 15-001 or 15-002.

Thanks for any info.
User submitted photo of their Caldwell sash balance.
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Mike from SWISCO responded:
Good Afternoon,

Very nice pictures, I have them marked for review by a window expert here. Quick question though, can you respond back here with the stamp that you should be able to find on the metal channel (it may be a little faint). The stamp helps us to determine the strength of the replacement balance you will need.
A home owner from Florida says:
Yes there is a stamp on the backside of the channel. It says "28 3 FP CALDWELL". Those are the only markings on the channel, unless there is something inside that is covered up by the spring and inner workings.

Thanks for the quick response.
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Donna from SWISCO responded:
Looks like a 29" Series 390 Balance, with the 19-002 Top and 15-001 Shoe attached.

A 28 3 stamp normally translates to 2830
To check, remove the window sash and place it on a scale.

The 29" Series 390 with Stamp Option 2830 will carry a window sash weight range of 16 through and including 23 pounds.

This information is based on 2 balances per sash. Balances are designed assuming friction in the jamb weather-strip will carry a portion of the sash weight. Suggested sash weights are approximate.
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