Basic idea is the driver board, via solenoid section transistors, ground out the inputs on the sound board that trigger sounds. Since the sound board can produce the "beat me" words via the diag button, you need to look at the triggering. Inspect the header pins on the sound board and the driver board, that is the most likely failure point. Next try manually grounding the inputs on the sound board and see what you get. One input is to silence all sound so you can look for that. If all inputs to sound board are good, but one isnt triggering check the 4050 buffers on the sound board right after the input header pins. Finally check / replace the PIA.