Single Hung Window Balance Springs

Question

I need to know which replacement balance springs to order. The balance springs are 26" long with the writing numbers/letters of 25 3 JW CMC 11. Four pictures are attached for your information.

Thanks,
Bud

Bob · Accepted Answer

Hey Bud. This looks like either an S380-26 or S385-26. The only difference between these two balances is the depth of the bottom nylon shoe, or the measurement from heel to toe. See the diagram below for reference. Compare both balances with your old one to see what matches best. In either case, for a new stamp option choose 2530.

Comparison of the S378, S380 and S385 balance shoes.