I'm working on a Whirly Bird. It's not a pinball machine, but uses pinball parts.
The part in question is part of the assembly that dings the bell when you score points.
I had to replace the coil because it was burnt to a crisp.
When the coil is energized, it pulls the metal slug up from a resting position and it contacts a bell, causing it to ding.
I have all of the parts except for whatever is supposed to be attached to the metal slug. I assume it would be some kind of rubber part so that you don't hear the metal on metal contact.
I am also looking for a replacement for the rubber stop at the "at rest position". The currently is a rubber grommet there, but it is ready to fall off due to it being pretty dried up.
Here are pics: