As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FLIGHT 3373 DURING CRUISE FLIGHT AT 29000 FT GOT "PTRIM BACKUP INOP" WARNING ON EICAS. COMPLIED WITH CHECKLIST "TRANSFERRED TO NRWC 658-DFW-01173". THE AIRCRAFT WAS REMOVED FROM SERVICE. REPLACED HORIZONTAL STABILIZER ACTUATOR AS PER AMM 27-40-02. OPS CHECK GOOD AT THIS TIME. AIRCRAFT RETURNED TO SERVICE.