What was found
(CAN) DURING CRUISE , LEFT AC BUS CAUTION LIGHT ILLUMINATED. CAPTAIN ELECTED TO RETURN TO DESTINATION FOR TROUBLESHOOTING. MAINTENANCE FOUND THE LEFT AC BUS CONTACTOR WAS STICKING INTERMITTENTLY . THE CONTACTOR WAS REPLACED AND AIRCRAFT RELEASED BACK TO SERVICE. THIS PART IS ON A 7200 HR BENCH CHECK MAINTENANCE INTERVAL BUT THE OPERATOR HAS FOUND IT MORE EFFECTIVE TO REPLACE THE CONTACTOR WITH A NEW UNIT . THE FAILED CONTACTOR HAD COMPLETED 1850 HRS SINCE NEW. (TC# 20190621012)