Window Parts Replacement

Hi Arie. This is called a channel balance. It's a spring-loaded mechanism that indeed moderates the opening and closing of the window. I believe we can replace this for you, but we'll need more information, as that code doesn't tell us the exact identity of the balance. We will need to see the nylon fittings on either end of the balance, preferably removed from the window. If you could confirm the length of the metal channel, not including those end fittings, that would be a big help also. From there we should be able to narrow this down. See the videos below that entail how to remove and replace non-tilt window channel balances, as well as how to identify replacements. 

Thanks for getting back to me with these photos, these are most helpful. It looks like you have either the S380-24 or S385-24. The only difference between these two kinds of channel balances is the depth of the bottom nylon shoe, or what you can consider the 'heel-to-toe' measurement. See the diagram below for reference. Compare both with your old hardware to see what matches best. In either case, for a new stamp option choose 2320, which corresponds to your old balance's stamp of 23B. Let me know if you have further questions!

Comparison of the S378, S380 and S385 balance shoes.