As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT FL400 PITCH MISTRIM ANNUNCIATED IN OUR PFDS. UPON DISCONNECTING THE AUTOPILOT, THE ACFT PITCHED DOWN. NEEDED SIGNIFICANT BACK PRESS TO HOLD ALTITUDE. NOTICED THAT THE TRIM WAS JAMMED IN POSITION, WOULD NOT MOVE ELECTRICALLY NOR BY HAND. UPON DESCENDING INTO WARMER AIR & AT 9000 FT WE NOTICED THAT THE TRIM WAS UNJAMMED. WORKED NORMALLY THROUGH FURTHER DESCENT & TOUCHDOWN. REMOVED AND REPLACED THE LEFT AND RIGHT ELEVATOR TRIM ACTUATORS PER CE-560XL MM CH 27-32-03. OPS CHECKS GOOD.