As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN RETRACTING SLATS AFTER TAKEOFF A THUD WAS FELT AND SLATS WOULD NOT RETRACT. SLATS UNBAL. MESSAGE APPEARS ON EICAS. SUB: VISUALLY INSPECTED LT AND RT WING SLATS WITH NO DISCREPANCIES NOTED AT THIS TIME. PERFORMED FLAP / SLAT RIGGING TEST IAW AMM 27-50-00, 27-80-00, AND 27-50-05. FLAP/SLAT RIGGING TEST IS GOOD AT THIS TIME.