Need help identifying window spring for replacement

Question

Hi,

I'm helping my neighbor with this and I realize the pictures she sent may make it a bit difficult. If need be, let me know that you need new pictures and I'll ask her to give me the spring and I'll photograph it. Right now, she's avoiding that as she's older and our area is "sheltering at home" due to the coronavirus.

The side of the spring says "25 4 FL Caldwell." The attached pictures show the nylon connectors.

Casey · Accepted Answer

Hello,

It looks like you have either our S351-26, with a 15-002 bottom attachment, or S390-26, with a 15-001 bottom attachment. Take a look at the image below to determine which balance you'll need. You'll also need 2540 spring strength options for your replacement balances based on your existing stamp number.

Comparison of the S351 and S390 balance shoes.