Traco Double Hung Window Balance

A handy person from Jersey City, NJ says:
I have a traco double hung aluminum window. It will not lift due to 1 of the balances. I removed both and found that they are 2 different sizes with 2 different weight ratings. Is there any reason that this should be? I weighed the window itself and it is about 75lbs. Can you recommend replacement balances?
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Paul from SWISCO responded:

Greetings from Swisco! I think we should be able to recommend replacement balances, but we'll need a little more information first. If you can send us over the diameter and length of the tubes, along with photos of the balances, and any stamps on them, we should be able to take it from there.

A quick learner from NJ says:
Sorry - I thought I had attached a photo of the tubes but I guess it didn't upload.

One is 44" rated for 80lbs

The other is 38" rated for 69lbs.

The diameter appears to be 5/8"

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Tom from SWISCO responded:

Aha, okay. I recognize this balance. This is a specific type of heavy duty spiral balance that will need to be specially made.

You mentioned before that these two different sized balances are in the same window, though. This should not be; both balances should be identical. Do you have another window in the house just like this one that may still have its original hardware? 

In the meantime, please give me the total height of the track where the balance goes, as well as the height of the visible glass for the sash these balances support. If you would be able to give me the exact weight of the sash, that would also be a huge help. You mentioned before it's about 75 pounds, but I would like you to be as precise as you can. 

While you look into that, we will continued to research the best solution for this problem.

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