As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RED GEAR LIGHT CAME ON AFTER RETRACTION WITH AURAL WARNING ON IN UP POSITION, GEAR UNSAFE CHECK ACCOMPLISHED PER FHB PROCEDURES AND RETURNED FOR LANDING. T/S FOUND A-9 CARD IN ALT CONTROL BOX FAILED. REMOVED AND REPLACED CARD PER AMM 32-61-00.