As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
STABILIZER TRIM AND MACH TRIM CAUTION MESSAGE CAME ON AFTER TAKEOFF. FOLLOWED QRH, WOULD NOT RE-ENGAGE. AIRCRAFT RETURNED TO THE FIELD. CAT II. REMOVED AND REPLACED FIRST OFFICER''S PITCH TRIM DISCONNECT SWITCH IAW MM 27-41-30. PERFORMED STABILIZER TRIM OPS AND FUNCTIONAL CHECKS IAW MM 27-40-00-710-801. OPS CHECKS GOOD, NO DEFECTS NOTED.