And she lives and speaks AGAIN!
Woo Hoo!
I tested the 7805 - it was putting out 4.9 volts, so I figured what the heck. I had SilPads from
@security0001 's Arcade Parts and Repair, and a 7805 in stock, let's just replace it. That got the voltage up to 4.98 VDC, which was better. Nice, new SilPad installed, new Fairchild (Radio Shack leftover) 7805, let's see what we get. I re-seated the connection cable, screwed it in, and everything is back. The voices tend to break up, I did futz with the potentiometers on the Sounds Plus board, but think I have a bunch that were the wrong size for the Chicago Coin sound board, so I'll pull that and replace both if the ratings match, and see if that helps.
Xenon is a really great pinball machine, but without the sounds, it was not as much fun.