As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER CONFIGURING FOR LANDING LEFT HYD QTY DROPPED TO 2 QUARTS WITH THE LOW LEVEL LIGHT. ACCOMPLISHED PROCEDURE, PRESSURE REMAINED NORMAL UNTIL TAXI WHEN LEFT PRESSURE DROPPED TO 0 PSI. FOUND LOOSE B-NUT FITTING AT TOP END AND BOTTOM END OF LEFT THRUST REVERSER CONTROL VALVE LINE. TIGHTENED NUTS, RAN ALL HYD PUMPS FOR LEAK CHECK WITH NO LEAKS. HYDRAULIC QUANTITY AND PRESSURE ALL GOOD.