As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE FLIGHT, THE CREW NOTICED THE RUDDER & AILERON TRIM TABS BECOMING VERY STIFF & DIFFICULT TO OPERATE. THE ACFT WAS EXPOSED TO MOISTURE & FREEZING TEMPERATURES THROUGHOUT THE DAY. DURING LANDING TRIM OPERATED NORMALLY WITHOUT ANY ISSUES. REMOVED MOISTURE & LUBED TRIM ACTUATORS. ACFT WAS RETURNED TO SERVICE.