As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BEFORE DISPATCH SEVERAL STATUS MESSAGES APPEARED ON EICAS-MAIN BATTERY CHARGER, EXH NR1 AFT EQUIP WITH FLUCTUATION OF CTR HYD QTY. COMMON 115 VOLT AC FOR ABOVE SYS IS A2 PHASE OF 115V AC GROUND SVC BUSS. WD 24-51-52. FOUND TWO LUGS ON GROUND SERVICE TRANSFER RELAY A3 & B3 SEPARATED FROM MOUNTING BASE. REPLACED RELAY. RAN ENGINE IAW JRH. OPERATED SYS WITH GRND POWER & APU POWER. SYS OPERATED NORMAL.