Do I have a series 775 channel balance?

Thanks for your photos. It does appear you have our S775-28 tilt channel balance with the exception of yours being a screw at the top of your balance and not a hook. In order for you to choose the most appropriate balance for you, you will need to choose the spring weight that is stamped on your current balance as well as on the bottom balance shoe. It will either be 1" wide or 1-1/4" wide. Get back to us and let us know how you made out.