As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
GEAR LEVER SELECTED UP AND NOSE GEAR WOULD NOT RETRACT GEAR. HANDLE SELECTED DOWN AND REMAINED DOWN. WHEN THE ACFT FIRST LEFT THE GATE A BUMP COULD BE HEARD WHEN THE TUG WAS FIRST CONNECTED TO THE ACFT. (EMERGENCY DECLARED -- A/C RETURNED TO DEPARTURE DUE TO MX)