What was found
AIRCRAFT RETURNED TO PLATFORM AS DUE TO AUTO SLAT FAIL LIGHT, THE STALL COMPUTER WAS REPLACED AND FAILURE CONTINUED, THE CONNECTORS OF STALL COMPUTER WERE CLEANED AND BOTH ACTUATOR CONNECTORS WERE RESEATED, TESTS WERE PERFORMED OK. DURING TAXI THE SAME LIGHT ILLUMINATED. THE ACTURATORS WERE FOUND WITH EXCESSIVE GREASE IN SLAT DRUM CAUSING FAILURE. SENSORS D1-55 AND D1-56 IN THE DRUM WERE CLEANED. SYSTEM WORKING CORRECTLY.