What was found
AT 2500 FT DURING CLIMBOUT SPEED 200KTS, LANDING GEAR HORN ON, UNABLE TO SILENCE IT. `NO ABNORALITIES ON GEAR INDICATION. CYCLED GEAR, WITH HORN OUT WHEN GEAR SELECTED DOWN, HORN ON WHEN GEAR SELECTED UP. DUMPED FUEL FOR MAX LANDING WEIGHT, RETURNED TO AIRFIELD. LANDING NORMAL. REPLACED LT O/B FLAP POSITION XMITTER IAW 27-54-02 ADJUSTED IAW 27-50-00 OP'S CHECK GOOD. REPLACED LEFT O/B FLAP POSITION XMITTER CONNECTOR IAW 20-30-05, NO DEFECTS NOTED. SWAPPED NR 1 & NR 3 DEU IAW 31-61-02, OP'S CHECK GOOD. A/C RETURNED TO SERVICE.