balance springs for my windows

Thanks for contacting us. If your balance tube is 3/8" in diameter, then I recommend our S400-29. Look this over and let me know what you think.

Your sash probably cannot be removed. Most non-tilt sashes that use this kind of balance aren't designed to be replaced. You'll need a charging tool like our 75-005 to charge the balance and hook it into a hook which is most likely in the bottom corners of the sash, tucked away and out of sight. Using the tool to hook the balance in will make life a lot easier than trying to do it by hand.