Can you confirm the diameter of the tube? There is no balance I know of that has a 1/2" tube. I'm pretty sure it will either be 3/8" or 5/8". It could even be 9/16", but that is considered 5/8" in the trade anyway. Can you also tell me what the weight of the window sash is? That's the only way to determine what color tip you need. Finally, when measuring the balance length, make sure that you're only measuring the tube.