trying to find the right channel balance (im guessing these are old)

Hi there!

I'm not able to identify your channel balance without photos. Can you remove an undamaged balance from the window and show us some photos? The related video will detail what we'd like to see. 

Note, your 2490 stamp is outdated which means we'll need to know the weight of the window sash in order to re-calibrate the spring strength.  

Thank you kindly for getting back to me. If the balance's bottom fitting is 1-3/32" deep then you would want the S385-25. However, note that the 28 number at the end of the stamp sometimes indicates the sash weight. A pair of balances with the 2460 strength option can support a sash weighing 27 to 30 pounds. Just something to keep in mind.

For a 16.4-pound sash, I'd recommend the 2430 stamp for a sash weighing 15 to 19 pounds. And yes, you're correct! You always want to replace the balances on both sides of the window at the same time. 

Comparison of the S380 and S385 balance shoes.