Block and Tackle window balance

A quick learner from Howard, OH says:
Vinyl Single Hung (only bottom tilts for cleaning). About 20 years old. Don't know brand. Need several balances. I believe they are block and tackle, (see pics), but they don't have the metal "channel" I see on all of them on your site.

Window will "pop" open about 6" when unlatched. I can open it farther, but it will fall back to the 6". To close, need to hold down with one hand and latch with the other.

Has a spring at bottom, 6" plastic piece and then the rope/string connects to a screw at the top. Can you help?

Thanks
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Bob from SWISCO responded:

This is an old rod balance that is no longer made, but it should be replaceable with one of our plain tilt window channel balances here. To know which, please show us whatever shoe, fitting or hook is at the bottom of the balance rod. Its design will tell us what you need.

A quick learner from Howard, OH says:
Does this pic show bottom of balance rod? Or is it all the way at the bottom of the spring?
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Bob from SWISCO responded:

No, that's just the middle of the balance. The part I need to see is all the way at the end of the balance assembly, where the shoe connects to the sash.

A quick learner from Howard, OH says:
Here are more pics.
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Tom from SWISCO responded:

Hello! Bob's not here today but I can help. These new photos you've submitted are perfect. I think I know just what you need.

Before I recommend anything though, you should first check the diameter of the spring to ensure that it is 1/2". If it measures anything else, you can ignore everything I'm about to say. Just let me know if that's the case and we can work from there.

Otherwise, if you have a 1/2" diameter spring, then you can use our Series 795 as a substitute. Now the process of converting to the Series 795 is a bit involved so I highly recommend watching the video below. This will walk you through the process step by step so that you can get these windows working again.

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