This was a neat one because I have not encountered a soundboard issue like this one before. In my short experience with Williams sound boards for games like stargate and joust, they have been an "all or nothing" kind of deal. This one however was missing sounds.
To troubleshoot this one, I did a few things. When I booted the game up I pressed the test button on the soundboard, it should play game sounds in general, but this just played tones. What this told me was that the CPU, DAC (probably) and amplifier area was working on this board. My guess immediately turned to the EPROM or 6810 Bipolar RAM. I started with the EPROM, what I did was that was dump the ROM and validate it with ROMIdent. The ROM checked out just fine. From there, I decided to test and socket the 6810 since I have had the worst luck with RAM ICs this year and I was replacing the sockets for the ROM and CPU anyway. Using my ABI Chipmaster, I verified that the RAM was indeed failing. After putting a new one in and testing the sound board again, it was working as it should.
I did a little video demonstrating what I was hearing since sound is not the easiest thing to describe: