Coil Balance Spring

Thanks for posting. That looks like a 15-228 Pivot Shoe, which uses either the 1/2" thick Series 160 Coil Balances or 3/8" thick Series 165 springs. Measure the thickness of your old springs to confirm which balance Series you need. You'll also need to choose spring weights for the replacement springs. These spring weights indicate the weight each individual spring can support. Look for stamps on the old springs that indicate this. If there are none or you're unsure, give me the exact weight of the window sash these balances support, and I can work it out for you. 

Thank you. Were you also able to verify which size spring you needed between the Series 160 and Series 165? That will affect which weight option we go with, since they're calibrated differently.

Thanks! So in that case, I recommend using one 5 pound and one 6 pound spring per side. That will give you 11 pounds of support per side, which adds up to 22 pounds. That's still half a pound short, but you won't notice the difference during operation.

Please feel free to reach out if you had any other questions!