What was found
FLT 320: TEST FLIGHT, LANDING GEAR LEVER WOULD NOT GO UP AFTER TAKEOFF. WARNING HORN ON AFTER FLAP RETRACT. RETURNED TO SJO, UNEVENTFUL LANDING. PERFORMED ADJUSTMENT AND TEST FOR THE GROUND SPOILER INTERLOCK VALVE CABLE AS PER MM 27-62-51, PAR 2 AND 3. PERFORMED LANDING GEAR EXTENSION AND RETRACTION AS PER MM 32-32-0, PAR 3 TO 5. SATISFACTORY CONDITION. AIRCRAFT RETURNED TO SERVICE.