Broken balancer shoe
Your balance shoe appears to be a match for the 15-177 Coil Balance Shoe. I'm quite confident this is the correct replacement but be sure to review and compare the specifications.
The springs compatible with this shoe are the Series 152 Coil Balances. They are attached using the 33-072 screw. To determine the correct coil weight option, you'll need to look for a stamp/marking on the metal.
If you can reuse the covers, that would be suggested. Your exact covers aren't available any longer but the 15-143 Coil Bushing, 15-144 Coil Bushing Cap, and 15-145 Coil Support Barrel will work, in the event that you cannot reuse them.