As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT MAIN GEAR INDICATED UNSAFE POSITION ON GEAR EXTENSION. MAIN GEAR DOWNLOCK SWITCH INDICATES GREEN. GEAR WARNING HORN COULD NOT BE SILENCED. PULLED P26 AND SILENCED HORN. LANDING UNEVENTFUL. CREW RECYCLED GEAR. RERACKED PROX CONTROL BOX. OPS CHECKED GOOD. EVIDENCE OF WATER ON TOP OF BOX. REPLACED WITH PROX CONTROL BOX FROM FLY AWAY KIT. OPS CHECKED GOOD IAW DC9 MM 32-60-01.