As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
STAB TRIM AUTOPILOT SWITCH IN CUTOFF POS CREW REPORTED SPEED TRIM FAIL. AIR RETURNED TO IAH UPON MEETING FLIGHT CREW, FOUND AUTOPILOT STAB TRIM IN CUTTOFF POSITION, REF FIM 22-11 TASK 849 PERFORMED SPEED TRIM TEST, ALL TESTS PASSED, NO PREVIOUS HISTORY IN 90 DAYS ADD EMP:U393391