Symphony orchestra, no PA. Live it sounded fine, and the waveform didn't look obviously bad in the basic view in Wavelab, but you could hear a problem on playback and the frequency spread in iZotope showed that for a few minutes the low end was winking out and on, sometimes there were "holes" other times stuff was missing but just weak not gone entirely. A loud passage might bring it back for a moment, then it would go out again.
I cleaned all contacts, replaced the 9V cell in the MMA6000, then thought better of it and swapped out to a backup MMA6000, same mics and recorder last night and no problems. But of course that could be luck, it ran fine for over three hours with just four-five bad minutes the night before.
I just hate these random fails.
Jeff