As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING DESCENT, VERTICAL SPEED WOULD NOT RESPOND TO INPUTS USING THE VERTICAL SPEED KNOB WITH A FCC AS THE MASTER. RESPONSE WAS IDENTICAL WITH AUTOPILOT ON OR OFF. VERTICAL SPEED WORKED NORMALLY WITH B FCC AS MASTER AND DURING CLIMB WITH EITHER FCC AS MASTER. PERFORMED DFCS BITE, NO CURRENT FAULTS AND NO SIMILAR FAULTS 90 DAYS REPORTED. PRECAUTIONARILY REPLACED FCC-A REF AMM 22-11-33, TESTS GOOD.