Jady,
It would be good to know exactly what this da da da sound actually is. Does it sound recognisable, or maybe its a sound the sound board normally doesn't produce. The things that come to mind are:
1. Sound Board. Maybe its something faulty with the sound board. I've just had a quick read through Clay's guides (searching on the key word of "sound"), and there are things that a faulty sound board can do to the rest of the game. With respect to the sound board topic, I would try (a) pressing the main self test button through the sequences until you get to the sound board test to see if the sounds produced are OK, (b) apparently the sound board itself has a self test button - see what this does (Clay's guide has more info on this), and (c) try removing the connectors to the sound board to see if the problem goes away.
2. Stuck switches. Just to make sure there are no switches stuck, main self test button again to diagnose. I suspect though that you do not have any stuck switches.
3. Interesting that the problems seem to occur after the outhole kicker is activated. Possibility of a faulty diode across the outhole kicker solenoid, with the back EMF causing this problem? Not sure.
