Help identify a replacement
Thanks for reaching out! Your pivot shoe appears to be an older discontinued version our 15-177. To determine if this replacement will work for you, you'll need to remove your existing shoe from the window and compare the dimensions to those shown below.
These are compatible with the 1/2" thick Series 152 coil balance springs. To determine the correct spring strength for a particular sash, you'll need to look for any stamps/markings on the metal coil(s) in the window. If there are no stamps/markings or they are hard to read, you'll need to obtain the exact weight of your sash. Once you have the sash weight, you'll divide it by the number of coils in the window.
To install the coil to the shoe, you will need to slightly unroll the coil so that you can fit the coil into the slot at the stop of the shoe. Then you'll need to secure the coil to the shoe using the 33-072 .
You may also need the 15-143 coil bushing, 15-144 coil bushing cap, and the 15-145 coil support barrel.