Had been sitting at only 18 Hz for an hour, when it tripped. Tried "reset", "off", "on" several times. No dice. Tried this sequence at 2 or 3 different pump frequencies. No dice. Tried to power cycle the controller by pushing in, then pulling out the big red panic button, and redoing the sequence of reset-off-on. No dice. Kept trying the sequence. Finally, after 3 minutes of this, it came back on.
Figure 1
