As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FLIGHT 3403 CREW REPORTED SEAT BELT/NO SMOKING SIGN AT 17A IS MISSING AND SPARKS WERE COMING FROM THE WIRES WHERE THE SIGN WAS LOCATED. DEADHEAD CAPT SEPARATED THE WIRES AND THE FLYING CAPT TURNED THE SEATBELT/NO SMOKING SIGN SWITCHES OFF. AIRCRAFT REMOVED FROM SERVICE. ISSUED MEL FOR SEAT BELT SIGN, INSULATED WIRES, REPLACED SEAT BELT SIGN. MEL RESTORED. AIRCRAFT RETURNED TO SERVICE.