As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ALITUDE SELECTOR ON MCP WON'T CHANGE CORRECTLY. AICRAFT RETURNED TO BLOCK AND WAS GROUNDED BY MAINTENANCE. REMOVED AND REPLACED MODE CONTROL PANEL IAW AMM 22-11-02 ACC'D MCDP TESTS 04, 30 AND 40. NO FAULTS-PART EFFECTIVITY VERIFIED. A/C RELEASED CAT 111B OPERATIONAL