Took apart drain pump. Water was in the impeller magnet area, which I think was making the noise. Cleaned out and resealed (need to replace seal obviously) and now no noise from drain pump.
On another hunch, I ran just a rinse cycle. Still overflows. Even with the overflow switch (which I have tested for continuity and found to be good) manually engaged (safely). I notice that the fill never stops running. So, I am beginning to thing this is either a bad fill switch, which never turns off, or a bad timer on the board, which never turns off. I am going to now test the fill switch. If it is "always on", then it is a bad switch. If it is not, it must be a bad board.
Any thoughts would be appreciated.