Lower sash balance coil springs.
Hi Paul,
We do not have this exact pivot shoe but the 17/32" thick 15-199 should work to replace it. Carefully compare the specifications below to confirm it will be a fit.
The compatible pivot bar is the 26-378.
This shoe is compatible with both the 1/2" wide Series 160 (uses the 15-150D double support) and the 3/8" wide Series 165 (uses the 15-204 dual support). To determine which of these is the correct replacement, you'll need to confirm the width of your coils. Unfortunately, I cannot tell that from the photo of the measuring tape.
I believe you'll need either the S160-06 or the S165-6, but you may want to make sure to double check whether the sash weighs 24lbs.