As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AUTOPILOT DOES NOT KEEP THE SAME ALTITUDE WITH ALT HLD PITCH MODE SET CMD A. ENGAGED ON A AUTOPILOT-AIRCRAFT OSCILLATES - + 50 FEET UP TO 400 FT/MIN WHEN ENGUAGED IT PUSHED. REPLACED FLIGHT CONTROL COMPUTER IAW MM 22-11-33. OPS CHECKED GOOD.