What was found
CAPT REPORTED AFTER T/O AND UPON RETRACTION, GOT SLAT DRIVE EICAS MSG - REPEAT DMC-B787-A27-80-F1-29A-421A-A ACCOMPLISHED.DURING WIRING CHECK FOUND PLUG D1284P OUT OF PLACE AND LOCK BROKEN. CONNECTOR, ELECTRICAL PLUG SHELL P/N BACC65BJ-F REMOVED & REPLACED IN POSITION D1284P IAW SWPM 20-74-14. NO WIRES DISCONNECTED DURING REPLACEMENT.HIGH LIFT SYSTEM TEST, SLAT PRIMARY FCM L/R/C ACCOMPLISHED IAW DMC-B787-A-27-80-F1-29A-421A-A OK.FLAPS/SLATS OPERATIONAL TEST ACCOMPLISHED, ALL SATISFACTORY.