Quoted from HELLODEADCITY:
I'd have a clear message underneath the glass behind the flippers
something like 'abuse of our games/equipment will get you banned for 1 year'
then have photos of game abusers like wanted pictures from the ole West posted on a wall
with a 'dime out' phrase at the bottom 'if you see this person report them at once and receive a __ '
The only thing you abuse by hitting a solid wood/ metal object is your wrist.