Window balance springs
A handy person from Manhattan says:
August 11, 2016
Hi! Spring broke. I'll have to wait ages for guys to come fix it and it's hot and humid ! I can't see any markings on the bar, which is 31 inches long, not counting the plastic bit. I'm fairly handy and expect to be able to install it myself. The bar is about 9/16, I guess 5/8. Thank you so much!
Tom from SWISCO responded:
August 12, 2016
Thanks for posting! If the balance is the only thing broken, see our Series 600 spiral balance. This has an outer tube diameter of 5/8", though it can work for 9/16" as well. Also see the video below for further information.