Find the other Allen bolt laying somewhere in there - they came loose & the coil bracket fell off. Add a dab of thread lock to the bolts & re-attach the coil.

Looks like this:image_(resized).png

You can get it at any automotive or home improvement store - locktite or threadlock are the common names for it - get the blue color - it's not as strong as red. It prevents bolts from shaking loose. While your at it, look at the other flipper mechanisms on your game - WOZ has been known to shake the mechs loose - not just the bolts that came loose on yours, but also make sure the nut/bolts are tight holding the flipper shaft also.

I agree things weren't tightened right so I'm just saying while he's under there may as well check the other flippers also... Mine loosened up & the nut fell off on the left flipper mech early on - can't hurt to check.