Now is the missing sound the laughing "duh-nuh, duh-nuh, du-nuh?" after he stomps on the girders? I always recall hearing that sound when playing it. And I never noticed any missing sounds when playing my 60-in-1 side-by-side. It sounded different, but nothing missing as far as I could tell.
But there is a balance pot on the game board set that sets the mix of the analog and digital sounds- it may have been touched or rattled in the move. I think the balance pot is on the 4th board (the sound board)- near the top. The sound board is the smallest of the 4 boards and the far right side of the cabinet. This pot is not near the two black pots on the top of the PCB. It is also NOT the same pot as the volume pot, which is next to the monitor. Also, one thing to note... the DKII kit replaces some of the original roms, so it's possible it may sound slightly different than what was originally in the machine. And it's also possible that replacing the PCB ROMs may not fix the issue at all. Maybe the kit is to blame? You can always remove the kit from the z80 chip and then take the z80 off the DKII kit, and place it back in its original socket- to see if there's any change in the sound.
Here's a thread about someone adjusting that pot.
http://forums.arcade-museum.com/showthread.php?t=23395
And here's a picture I took- it's the white round dial in the top left corner of the PCB.
Donkey Kong II installed by
mhanlen1, on Flickr
As far as Asteroids goes, I actually turned it down from when I first got it because it was too loud. The only thing is, I played it in a quiet room, so it didn't have to compete with the attract mode of the other machines. I know the sound peg isn't easy to turn, so you may try with a pair of pliers, if you haven't already.
Had I known about this thread earlier, I would have responded, but I normally only get to check KLOV once a day. Feel free to call me.