The chimes were rebuilt prior to deciding to attempt adding sounds to the game...so yes they are obsolete now.
My plan now is to use a WAV Trigger as the sounds & voices player and the Uno as the controller, similarly as you did with the Arduino. The WAV trigger has 16 inputs for activation sounds. It instigates them by grounding each of the 16 pins. Each of the 16 triggers can have 1 distinct or several random sounds/voices from each trigger grounding.
I suppose I could use the WAV Trigger without the Uno, by just using switches (double up on switches on some playfield) to activate the WAV Trigger, but that would mean limited added sounds or random sounds.
I thought of using the chime solenoids to activate switches to trigger sounds, since the game continually plays the chimes when the pinball hits things. But there are only 4 chimes, so there would be a lot of random sounds.
I was thinking that I could tap into the playfield and BBox lamps to trigger sounds, using an UNO. What do you think of that idea?