Improving gearbox reliability

IF A WIND TURBINE CAN LAST THREE YEARS AT A WIND FARM IN THE US, SOUTHERN CALIFORNIA'S SAN GORGONIO PASS WITHOUT MAJOR SERVICING, THEN IT SHOULD LAST LONGER IN AREAS OF THE WORLD WITH LESS TURBULENT WINDS. WHY THEN, ASKS FRONTIER PRO SERVICE'S JACK WALLACE JR. , IS THAT SOMETIMES NOT THE CASE? AND WHAT CAN BE DONE ABOUT IT?