Constant Force Balance

Thanks for posting! This coil assembly reminds me of the 15-180 Coil Balance Shoe. Carefully look over the dimensions below to confirm that this is the right fit.

Alternate image for 15-180

The compatible coil spring is the Series 190 Balance. Since yours is marked with a 602, you'll likely need the S190-640 but it may be a good idea to double check that the sash weighs 24lbs.

These are secured to the shoe using the 33-073 screw and anchored to the window track using the 15-181 Double Support Detent Clip and 15-182 Balance Bushing.