Fluid level trip.  Found the Pump Controller (not servo) red lite off--other than power failure, sure indication of Fluid Level trip.

Turn on Process:

Since I've hardwired the FWD button, the controller will start at the Servos Command as soon as the Green Start Button is pushed, so:

Must turn down the Servo Output--On Pump Controller medm set servo set point to zero or manually run down the output.

Press Green Start button on Controller Cabinet, Ramp up servo set point to 80psi, or step up output manually to near 80 and then switch servo to Auto mode.

Warning--Don't overshoot the pressure too much or the level may trip again or if you really overshoot and the level doesn't trip, the pressure relief valve will release.

After I got the servo running again, I pulled up the trip switch and found the trip level was only ~1/16" below the run level.  Of course to do this test you have to trip the switch and start all over again.  I then lowered the switch ~1/4" so we should be good for a while.

I have a scale on the site glass and a white board logging the running levels and now I have a trip level.  We have been trending down a bit over the past few months.  I have a couple minor leaks at the pump station, maybe something like a teaspoon a month.  That combined with evaporation and the large servo load (really minor affect I believe) led to the trip.  I'll start a regular maintenance routine of noting the running fluid level and lowering the trip switch to keep ahead of it.