What was found
AT TOP OF CRUISE EN ROUTE FROM LAS TO MEX "A" SYS HYD QTY INDICATED FLUID LEVEL AT THE REFILL LINE, SOON AFTER QUANTITY FELL TO .7500 FULL AND WAS INDICATING A DECREASING TREND, DIVERTED TO PHX AS PRECAUTION. MAINTENANCE INSPECTED THE AIRCRAFT FOR FLUID LEAKAGE, NO LOSS OF FLUID WAS FOUND, RAN BOTH ENGINES WHILE CYCLING THE FLIGHT CONTROLS, NOSE WHEEL STEERING, BRAKES, AND LANDING GEAR LEVER (WITH PINS INSTALLED), NO LEAKS WERE FOUND. "A" SYSTEM HYD QTY INDICATOR WAS OBSERVED TO STICK AT CERTAIN POSITIONS, REMOVED AND REPLACED QUANTITY INDICATOR IAW BMM 29-33-11, OPERATIONAL CHECK WAS GOOD. VENDOR TEARDOWN, CONFIRMED FAILURE OF UNIT. FOUND THE MECHANISM ASSEMBLY STICKING AND THE POINTER BROKEN.