As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
STAB TRIM CAUTION MSG IN FLT COULD NOT ENGAGE CHANNEL 1 OR 2 AT FLT LEVEL 340. CW QRH L.5 HRS LATER AT 6000 FT BOTH CHANNELS REENGAGED AND STAYED ENGAGED THE REMAINDER OF THE FLT. NORMAL LANDING FLAPS 20. AIRCRAFT REMOVED FROM SERVICE. PERFORMED SUP 05-029A. NO DEFECTS NOTED.