Need help getting correct parts and replacing please

Hi Ron. This looks like a Series 180 Coil Balance spring. If the stamp reads '7' you might need our S180-7 7 pound spring. If in doubt, weigh the window sash. Give me that exact weight and I can work out all the spring weights you need. These springs work with our 15-087 Pivot Shoe, 15-086 Coil Housing and 16-024 Bracket. See the diagram below. 

Detail of 15-086