A quick learner from Georgia says:
September 8, 2016
I have a house that has metal Jordan Windows from the 80's. Several are in need of new balances. On the balance it has an ink stamp "2430", which I'm hoping is the part number. Is this all I need to order new ones from you or do I need to take one apart and do measurements?
Tom from SWISCO responded:
September 9, 2016
Hey, Kent. I'm afraid that stamp isn't used in identification. All that tells us is how strong the spring is. Series identification is based only on the style and size of the nylon caps on either end of the metal channel. I recommend that you look at our Channel Balance Home Page and follow the steps in order to find the Series that best matches what you have.