Identify proper spring replacement

Question

Single hung vinyl window. Part stamp is 3030 BSL It appears to be a 1/2 inch channel.

What would the spring # be? It appears to one of your first listed channel spring shown on your page.

Emily · Accepted Answer

Hey there!

This looks like it may be either the S351-31 or S390-31. The difference between the two parts is the depth of the bottom shoe as shown below. I also recommend the 3030 stamp for your replacements.

Comparison of the S351 and S390 balance shoes.