Need replacement balance for Jeld-Wen tilt sash single hung window

What is the diameter of the outer tube? If it's 3/8", you need a Series 900; if it's 5/8", see the Series 600. To know what Color Tip to select, weigh the window sash. A bathroom scale would suffice. You can then match that weight with one of the weight ranges listed alongside each Color Tip option on the balance shop pages.