What was found
ON TAKEOFF PLUS 317 AT FL360 HEARD WHAT SOUNDED LIKE A TRANSIENT ELECTRICAL CHANGE OVER, HOWEVER ALL ELECTRICS APPEARED NORMAL. THEN NOTICED WHEN SCANNING OVERHEAD THAT GREEN HYDRAULIC RESEVIOR WAS IN YELLOW. WHEN POWER CAME TO IDLE FOR DECENT ECAM SHOWED LOW GREEN HYD. COMPLIED WITH QRH. GREEN PRESSURE/QTY CAME BACK (12 OCLOCK POSTION) WHEN GEAR WAS MANUALLY EXTENDED FACT 07JAN09 23:34 LAX U REMOVED & REPLACED GREEN SYS RESERVOIR IAW MM 29-11-11-4. PERFORMED OPS CHECK, FOUND NO LEAKS. CLOSED ALL PANELS PER SMP. ACFT OK FOR SERVICE.