As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LHR - BELT CAUGHT IN SEAT TRACK AT 4J AND SHORTED TRACKING AND SWIVEL MOTORS OUT. SMOKE WAS PRESENT. PULLED CIRCUIT BREAKER FOR SEAT 4J AND PLACARD PER 25-04D AUTHORITY 4-105DC-C. REPLACED LEFT BACK SUPPORT ARM ADJUSTED SWIVEL CABLE. SYSTEM GROUND CHECKED NORMAL OPERATION.