BSI balance replacement parts

A home owner from Raleigh, NC says:
We need two BSI 3600 LB balance replacements and one BSI 3000 FL balance replacement for our white vinyl tilt windows approx. 15 years old. They look almost exactly like the ones in your "how to replace" video. Can you help? We can email pictures if you need them.
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Tom from SWISCO responded:
Yes, images would help immensely. You can upload them here for us to see. Thanks!
A home owner from Raleigh, NC says:
Tom,
Our balances look identical to the ones in your "how to install" video. They also look like the ones in your Discussion/2900 BSI sash balance inquiry from someone in Charlotte, NC and Swisco labeled them S770 series.

We need two BSI 3600 LB balance replacements and one BSI 3000 FL balance replacement for our white vinyl tilt windows approx. 15 years old.

Thanks for your help.
Roy
User submitted photos of a window balance.
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Paul from SWISCO responded:
Thanks for the images, Roy, these are perfect. I agree, our Series 770 appears to be our best match. Specifically, I recommend our S770-36 and S770-30. Our options don't match your stamps, so you will need to weigh each sash to determine which would be best. We have a chart on each balance's respective store page showing how much weight each option can support, so all you have to do is refer there.
How to replace a tilt-window channel balance.
How to replace a tilt-window channel balance.
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