Unfortunately, it didn't sort itself out as we had hoped.  Head 3 was the cause of this trip, which was not surprising given the behavior we witnessed after restarting the laser after the night's previous trip.  The first attachment shows the 3 active laser head flow sensors and the relevant interlock signal.  The second attachment shows a slightly zoomed view of the signal from the laser head 3 flow sensor.  Nothing else looked suspect.

The system restarted without issue.  Given the behavior seen after the first trip, we observed the flow rates for several minutes before calling everything good to go; no issue was seen during this time.  Given the increase in frequency of this interlock tripping, I think we are witnessing 2 flow sensors on their last legs.