Request replacement parts for window channel balance

Thanks for posting. I agree, the Series 385 looks promising; the only other possibility would be the Series 380. The only difference between these two channel balances is the depth of the bottom nylon shoe, or the 'heel-to-toe' measurement. Compare the diagram below with your old balances to see which matches best.

Comparison of the S380 and S385 balance shoes.

These balances should all have metal channel lengths of 25", so go with either the S380-25 or S385-25. Finally, you'll have to choose stamp options, which designate the strength of the balances. Your guess that the letters at the end of the old balance's stamps designated their strength is absolutely correct--the only difference in our stamp system is we use all numbers instead of letters, but it's easy enough to translate. For instance, for balances stamped 24C, go with our option of 2430; for 24B, use 2420, and for 24A, 2410. Let me know if you have any questions about this. 

Finally, I can't tell who the manufacturer was either I'm afraid. These balances are used by a ton of different brands, so it's impossible to say based off them alone. That said, the good thing about brand-independent parts is it means there's always a chance of replacing them even if the old manufacturer went out of business--and that's the case here! Let me know if you ahve further questions.