Window channel balancer
Hello there. I am afraid those numbers don't tell us the balance's identity. Do you have any balances in other windows that the repair person didn't take that you can take photos of and show us? If not, he needs to return the balances to you so we can properly identify them. See the video below.
Thanks for getting back to me. This is either an S380-30 or S385-30. The only difference between these two balances is the depth of the bottom nylon shoe, as depicted in the image below. Compare both with your old hardware to see what matches best. For a new stamp option, choose 2950.
Sure, let me clarify. The stamp option designates the weight range the balance can support. For an S385-30, you want to choose a stamp option of 2950. I'm basing that off your old balance's stamp code, but this stamp option designates that the balance can support a window sash in the weight range of 28 through 32 pounds. Let me know if that makes sense.
See the video below that shows how to remove and replace these types of balances.