Constant force shoe
Thanks for your post! It looks like your post uploaded without your photos. Would you be able to try sending them again?
I'll need to see clear photos of the hardware, removed from the window to make the best recommendation. You'll also need to have them removed to compare the dimensions.
Please let me know if you have any questions.
Thanks for the requested photo. The shoe you have is the 15-180 Coil Balance Shoe. The coil spring is the Series 190 Coil Balance Spring, which is attached to the shoe using the 33-073 screw. This shoe is compatible with the 26-040 Pivot Bar.
Since your assembly uses only one coil, you may also need the 15-186 Coil Balance Clip (used with the 15-182 Balance Bushing). There is a video tutorial below with instructions on how to select the correct coil weight option.
There doesn't seem to be any visible damage to the spring, so if it is still in good, working condition you likely won't need to replace it.