As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLIMBING THROUGH APPROX FL270, THE LANDING GEAR UNLOCK LIGHT BEGAN CYCLING ON AND OFF ACCOMPANIED BY THE LANDING GEAR SLAMMING INTO THE UP AND LOCKED POSTION CONTINUOUSLY 1 TO 2 TIMES PER SECOND BEGAN A DESENT AND THE CYCLING STOPPED AT APPROX FL200 WHEN LOW ENOUGH AND SLOW ENOUGH THE GEAR WAS SELECTED DOWN AND GOT 3 GREEN LIGHTS NO RED.