As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING CRUISE, THE NR 1 HYDRAULIC SYSTEM WAS DEPLETING AND WAS DOWN TO 20% OF CAPACITY. NO ASSOCIATED EICAS MESSAGE. AIRCRAFT WAS DIVERTED TO MAINTENANCE BASE.LEAK WAS FOUND AT NR 1 HYDRAULIC PUMP. PUMP WAS REPLACED. AIRCRAFT GROUND RUNS CARRIED OUT, SYSTEM REPLENISHED AND AIRCRAFT RETURNED TO SERVICE.