What was found
DTW - FLT 640 - ON FINAL DTW, SLAT DISAGREEMENT LIGHT ON, BLUE SLAT AGREEMENT LIGHT FLICKERING, STICK SHAKER ALARM GOING OFF AT 130 KTS, (82,000 LB A/C CK REF 120) FLAPS 40 DEGREES NEEDED 155 KNT ON FINAL APPROACH TO LAND A/C. PERFORMED CONTINUITY CHECK ON LT AND RT SLAT RETRACT SWITCHES IAW CHAP 27-80-0. FOUND LT SLAT RETRACT SWITCH FAULTY. REPLACED SAME IAW CHAP 27-80-6. SYSTEM CHECKS GOOD ON GROUND. (M)