If I recall, there is a "blend" knob on the squawk and talk board that controls the amount of speech to sound effects. I could be totally misremembering the one I used to have. I know Williams System 6/7s have this feature. Give your board a check and see if the knob is just misadjusted or dirty. This may just be cutting off the speech.

No sweat, glad it worked out. I will say that a can of De-Oxit D5 is your best friend in the world. It will clean and lubricate that pot to keep it nice and reliable for a long time. Regular contact cleaner isn't even close.

Does the whole machine reset? or does it just start a new game on ball one? There are some things that definitely are suspect on these old games like the pins on all the connectors. If your game is resetting then it may be losing 5volts for a split second due to a crappy connection at the rectifier board. Obviously, all the pins are not good quality after 40 years, but the skinny orange wire on the long connector is the 5v line, I believe. Need to replace that for some reliability, as well as the pins leading to the boardset, then see if the problem continues.