As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRPLANE PITCHES CONTINUALLY IN A WAVE LIKE PATTERN WITH AUTO PILOT ON. ELEVATOR TRIM IS IN CONSTANT MOTION UP & DOWN A FEW TENTHS OF A DEGREE IN BOTH DIRECTIONS. FLT 4611 REPLACED MOTOR CONTROL UNIT & ELEVATOR SERVO IAW AMM. PASSED IN FLIGHT FUNCTIONAL CHECK. PN1 ON 7074-4, SN1 ON 302, PN1 OFF 7074-5, SN1 OFF 736, PN2 622-5027-101, SN2 ON 1LT8G & SN2 OFF 1KR0H.