Window coil spring top connector

I'm pretty sure we can help, though I think this might be more involved than just a connector. It appears the piece that broke is built into the spring mechanism itself, which means you may be in the market for new balances.

It's hard to tell exactly what you have based on this picture, though. If I had to wager, I'd say you have a 5/8" diameter spiral balance for a tilt window, which is our Series 600 . I can't be sure. Is there any way you can show me a picture of an undamaged balance? There should be an outer tube around the coil spring, likely white plastic in your case. This outer tube is used to determine the size. That would also let me see this connector piece you mentioned. Our balances don't use any such piece, but instead just have the screw go through the metal tube itself.

Our Series 600 balances use metal tubes and overall we find that they are sturdier and last longer than the old spiral balances which use that plastic outer tube.

Thank you! Looks like you have a standard tilt window spiral balance. If the outer plastic tube is only 3/8" in diameter, see our Series 900 instead. This should replace your balance system.