As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CAPTAIN'S SEAT SLIDES BACK ON TAKEOFF AND CLIMBOUT. DIFFICULT TO LOCK IN PLACE. REPLACED CAPTAIN'S SEAT IAW DC-9 MM 25-10-0. OPS CHECKED GOOD. SEAT WAS ROUTED TO SHOP WHERE FUNCTIONALLY CHECKED GOOD. SUBSEQUENT FLIGHTS HAVE HAD NO DISCREPANCIES.