What was found
DURNG FLIGHT LR-628, AIRCRAFT RETURN TO SJO STATION, BECAUSE IT WAS REPORTED THAT ISOLATION VALVE LIGHT ILLUMINATED AND TAKEOFF CONFIGURATION WARNING LIGHT CAME ON. AT SJO STATION, SWITCHERS WERE REPLACED AND TESTED SYSTEM IAW MM 32-33-11, IT WAS WORKING SATISFACTORY. AIRCRAFT RETURNED TO NORMAL OPERATION. (M)