NOS nylon ball cradle cap.
This attaches to the bell armature / plunger on the VUK with a roll pin.
If your VUK is inconsistent in pushing the ball up, examine this cup/cradle; it has 4 fingers on it.
I have seen many with 1 or 2 broken, the result, the ball will not be positioned correctly for the up-kick, and may, or will hit the sides of the wireform, loosing inertia prior to the apex, resulting in repeated attempts.
It is used on many titles.
This Cap / Cradle will only fit the thicker Data East / Sega / Stern nylon plunger tip; it can only be used on a Williams/Bally if you change the VUK plunger to a DE style.
Data East / Sega / Stern: 545-5227-00