Nick -
Just guessing, but you should have three chime bars - one each for 10, 100, 1000. These should energize whenever the score wheels turn. Find the point relay, and activate it. The player score should index and the chime should sound.
Its possible previous owner disconnected the chimes - take a close look at the chime coils and see if the power wire was lifted from the tab common to the three coils. Also, its possible there is a plug for the chime unit that is unplugged - I don't remember if Bally chimes were "modular" or not.