Balance replacement

I am confident we can help you locate this balance, but we need some help from you first. Could we have you send us another photo showing the nylon fitting on the opposite end of the balance? The nylon fittings on both ends of the balance help determine which Series balance to recommend. We'd also like for you to reconfirm your length measurement. Be sure when measuring the length, you measure from metal to metal only, excluding the fittings. 

Thank you for the additional photos. Have a look at both our S351-25 and S390-25 channel balance. These balances both look identical, with the exception of the depth measurement of the bottom balance shoe. The Series 390 has a bottom balance shoe that is 1-1/8" in depth. The Series 351 has a bottom balance shoe with a 1" in depth. You will need to measure your bottom balance shoe, the way it is shown in the diagram below, to determine which of the two balances is the better match. Whichever one chosen will go with a 2440 option that supports a sash weight of 19-24 pounds. 

Comparison of the S351 and S390 balance shoes.