MW spiral balance part numbers

A home owner from Franklin, MA says:
The picture I uploaded shows my window shoe and twist balance, I'm looking for help to make sure I order the correct replacement parts.

The balance diameter is 3/8 and I have 2 lengths in my windows 25" and 29". The tips of the balances are white, however when I try to select a balance that is 25" or 29" inches and 3/8" in diameter a white tip is not an option. Please advise as to what part I should select.

The shoe has a clear marking on it 590CSB. The shoe is curved on one end, so depending on where you take a length measurement you get 2 1/8" to 2 1/4" long. the shoe is 1 1/4" wide and is 9/16" thick. The shoe has a blue cam and there is a tooth in the center of the cam hole. The cam hole is 5/16" x 3/16". When I look at the pictures on your site, I see dimensions that align, but none of your shoes look like what the balance hooks look like on my shoe; perhaps it doesn't matter?

For reference, these parts came out of an MW window that was installed in 1998.
Thumbnail of the uploaded file named WINDOW PARTS.jpg
A home owner from Franklin, MA says:
Looking more closely at the information on the twist balances, I see that white is not usually one of your product choices, so I weighed the sash; it weighs 16 pounds. I think that puts me in the red or blue range; red on the 29" balance and blue on the 25" balance. My assumption is to be in the middle of the spring range. Please advise.
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Casey from SWISCO responded:

Hello,

Take a look and compare the specifications of the S900-25 and S900-29 to your spiral balance assemblies. As for your pivot shoe, the manufacturer that made your shoe has gone out of business but we usually suggest 15-118 as a replacement as long as the width and thickness match yours. 

As for the sash weight, I would recommend checking the sash weight for both windows with different sized balances since they could be different weights. If both weigh 16 pounds, you can use the red tip option for both lengths. Thanks for posting! 

A home owner from Franklin, MA says:
The upper and lower window sashes weigh about the same; only difference are the window locks. The original balances both had white tips, the only difference is the length. The upper sash use's the short balances; 25". The lower sash uses long balances; 29". Thanks for the info.
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Casey from SWISCO responded:

Great, then it sounds like we've identified the parts that you need. Please let us know if you have any other questions. 

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