OK.
If I am looking at the right bit - its known as a Reset Arm Bearing. The part number is A-15687.
Check with RTBB - Greg, he's got lots of Gottlieb parts. Otherwise PSPA has Gottlieb parts too.
That is the correct part number - common on EMs. If no one is parting out a Drop Target assy from a GTB - then I might have one I can give you