As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON T/O MCD A LIGHTS ON FWD ILLUM. FOLLOWED QRH RED TABS AND RETURNED TO AFW. A LIGHT WENT OUT ON FINAL. MAIN CARGO DOOR WARNING LIGHT SYSTEM (A OR B) INOP. VERIFY DOOR CLOSED AND LOCKED PRIOR TO EACH BLOCK OUT. CLEANED CONNECTOR ON SYS-A MICROSWITCH PER SMP AND RAN DOOR THROUGH SEVERAL CYCLES. OPS CHECK SATISFACTORY IAW NASI SYSTEM DOOR MANUAL FXV-727-MM14. OK FOR SERVICE.