What was found
(CAN) CREW REPORTED GEAR NOT RETRACTING, ACARS SAID IT WAS THE NOSE GEAR THAT DIDN`T COME UP & THEY CHECKED THE ALT DOOR & IT WAS CLOSED. THE TAKEOFF WAS NORMAL WITH THE MAINS COMING UP & THE NOSE WENT AMBER, BUT NEVER WENT UP. THERE WAS VIBRATION FROM AIRFLOW ON THE GEAR BUT NOTHING ABNORMAL & NO MSGS 06-08 1646. MX CALLED BACK & THEY DO HAVE FAULTS FOR PRESENT LEG. MX REPORTED THEY PERFORMED GEAR SWINGS & OPERATIONS CHECKED GOOD EVERY TIME. FURTHER TROUBLESHOOTING ON GOING, INVESTIGATING NLG DOOR ACTUATOR & LINKAGE ASSEMBLY.