Window balance

I'm not sure about this one. I see you purchased our Series 300 but I don't think that's it. Yours is very old. Before we recommend anything, can you tell me the diameter of the outer tube that goes over the spring? Can you also show me a picture of the sash and the track where this balance installs?

Thank you! I believe our Series 400 would be better for you. I would also recommend our 17-031 bottom bracket. You can use a 33-078 screw to install the the tube at the top of the window and the 33-073 to attach the 17-031 bracket to the sash. I also think our 75-004 charging tool will be helpful for installation.