Need Code for Replacement Channel Balance

See our S380-21 or S385-21. The only difference between these two balances is the depth of the bottom nylon shoe, so compare both with your old hardware to see what matches best. For a new stamp option use 2040.

Your old stamp, "20 4," is the same as our 2040. It's just stamped differently because it has a different manufacturer.

However, if your sash is 13 or 14 pounds then this is incorrect. 2040 would be too strong, as you pointed out. That means that whoever installed these balances used the wrong parts. You should trust your sash weight above anything else. The kind of people who install these balances will throw any old thing in there, I wouldn't trust them as far as I could throw them. They're just looking to get the job done. 

Long story short, if your sash is 13 pounds, go with the 2030. Just to be safe, you should get the exact weight of your sash down to the ounce. That way you're 100% sure of what you need.