Window balance springs needed maker unknown

Question

Hi,

My window balance broke, I need a new one. Can you please help to identify this and quote a replacement if possible? I'd love to get one ordered immediately.

Bob · Accepted Answer

Hello there. This looks like either an S351-31 or S390-31. The only difference between these two channel balances is the depth of the bottom nylon shoe, or the measurement from 'heel' to 'toe'. See the illustration below for reference. Compare both with your old balance and see what matches best. In either case for a new stamp option, select 3040.

Comparison of the S351 and S390 balance shoes.