pgt 36" X 36" sh storm gaurd impact rated window

Thank you for posting. I believe you have our Series 500 non tilt spiral window balance. Check it out and see if you agree.

I also believe that you can remove the bottom sash by unscrewing and removing the angle and balances. After that your window sash should come out, allowing you to see what size balance you need and if you need a new bottom bracket.