As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW WAS UNABLE TO RAISE THE GEAR AFTER TAKEOFF. THE GEAR HANDLE WAS IN THE OFF POSITION WITH THREE GREEN AND THREE RED INDICATION LIGHTS. THE AIRCRAFT WAS RETURNED TO EWR. TROUBLESHOOTING FOUND THE RIGHT MAIN GEAR SAFETY SENSOR OUT OF ADJUSTMENT. THE SENSOR GAP AND TELEFLEX CABLE WERE ADJUSTED IAW MM 32-09-01. A GEAR SWING WAS PERFORMED AND ALL OPERATION CHECKED GOOD.