What was found
(CAN) DURING UNSCHED MAINT ON FLAP RIGGING, LT INBOARD FLAP ACTUATOR DRIVE WAS DISCONNECTED AT FLAP ATTACH. FLAPS WERE FULLY DOWN (35 DEGREES). FLAP SELECTED FROM DOWN TO 17 DEGREES AND FLAPS TRAVELLED TO 17 DEGREES. THE LT SPLIT FLAP SWITCH ACTUATOR HAD MOVED OFF CAM BUT SWITCH HAD NOT STAYED IN DEPRESSED POSITION. SPRING MECH HAD NOT RELEASED. BY PHYSICALLY MOVING SPRING MECH ON SWITCH, IT MOVED TO OPEN POSITION. THERE WERE CARBON DEPOSITS ON SWITCH COMING FROM ENG EXHAUST AND BUILD-UP WAS SUFFICIENT TO PREVENT SWITCH FROM SPRINGING OPEN. SWITCH REPLACED. SUBMITTER STATED THIS IS 2ND SPLIT FLAP SWITCH TO FAIL FOR THIS COMPANY ON DIFFERNT A/C.