Quoted from Rikoshay:off topic a little, and not meaning to hijack your thread jeffthanksyou but i have read a few times about this 'buzzer' in various machines.
i just checked inside my Bally Old Chicago and sure enough there is a screw hole just under the ball roll tilt and two thick yellow wires joined together and a white/red wire at the bottom.
so at some point my OC had one and it was removed
now to find a suitable replacement?
Make that two of us.. I was looking at this and lo and behold mine is missing as well... geezus.