Searching for Window balance with stamp 26 4 IU CMC 2

Thanks for posting. I believe you have either an S380-27 or S385-27 channel balance. The only difference between these two types of balances is the depth of the bottom nylon shoe, or the 'heel-to-toe' measurement, so compare both with your old hardware to see what matches best. See the diagram below for reference. In either case for a new stamp option choose 2640.

Comparison of the S378, S380 and S385 balance shoes.

Great! I'm glad to hear you were able to find a good option. Please feel free to reach out if we can be of any further assistance.