Occasionally, the music will either stop playing or get hung on a single note. When the music changes, it usually starts working again. For example, the music will stop working, then when the ball drains and the music restarts on the next ball, the music will be back. I have seen "Music Error" when entering music test, but not every time; it's actually very rare that the issue shows up at all. I haven't noticed any problems with sounds or voice.
What I've done so far:
I've replaced the ribbon cables and cleaned the mating connectors with 99% alcohol. I have inspected the headers and nearby traces under my microscope. I have not replaced the headers yet since I didn't want to do board work without identifying the problem.
Any suggestions on where I should look next? I have an oscilloscope, but I'm not sure what to look at. It seems like it's probably a problem with a command that selects what music to play, but I don't know enough about how the music works to know what to look for.