As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CTR HYD QTY EICAS MESSAGE CAME ON, QTY SHOWED 0.48 WITH MAIN ELEC PUMPS OFF QTY HELD AT 0.41. AUX PANEL ISLN LIGHT ILLUMINATED. FOUND DIFF PRESS IND ON ADP PRESS MODULE CAME LOOSE. REPLACED PACKING AND REINSTALLED DIFF PRESS IND PER MM 29-11-0. LEAK CHECK OK.