What was found
RECEIVED AN EICAS MESSAGE FOR CREW OXYGEN LOW. THE FLIGHT DESCENDED TO FL 250 INITIALLY, AND THEN DESCENDED TO BELOW FL 180 WHEN THE OXYGEN LEVEL WENT TO ZERO PSI. THE FLIGHT DIVERTED TO ANC AND DECLARED AN EMERGENCY DUE TO OVERWEIGHT CONDITION. THE FLIGHT LANDED WITHOUT FURTHER INCIDENT. FOUND BOTTLE REGULATOR AND HOSE LEAKING. REMOVED AND REPLACED OXYGEN BOTTLE AND HOSE ASSEMBLY PER AMM 35-11-00-18A AND 12-15-08-00B-200A-A, LEAK CHECK AND OPERATIONS CHECK GOOD. THE AIRCRAFT WAS GROUNDED.