As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UNABLE TO MAKE EDITS IN LEFT FMC. SCRATCHPAD MESSAGE FOR INVALID ENTRY WOULD SHOW ON ALL FMC PAGES. NO OTHER INDICATIONS NOTED. ACFT GROUNDED. PERFORMED FIM 34-61 TASK 801, NEITHER FMC LOGGED ANY FAULTS IN FLIGHT FAULT HISTORY. FMC OPS CHECKED NORMAL IAW AMM 34-61-00. REPLACED THE NR 1 FMC IAW AMM 34-61-02. ALL INSTALLATION TESTS NORMAL IAW SAME.