What was found
(CAN) PILOT WAS IN CRUISE WITH LANDING LIGHT ON, WHEN SHE SMELLED SMOKE AND NOTICED SMOKE COMING FROM LANDING LIGHT SWITCH. SMOKE STOPPED WHEN SWITCH TURNED OFF AND PILOT SQUAWKED 7700 FOR HELP AND SHE WAS ADVISED TO LAND. AGAIN IT WAS CONFIRMED THAT THE SWITCH WOULD SMOKE WHEN TURNED ON, BUT NOT WHEN OFF. PILOT FLEW AIRCRAFT HOME WITH LANDING LIGHT OFF, WHERE MAINTENANCE CONFIRMED PROBLEM AND REPLACED THE SWITCH. NOTE: THIS IS NOT AN UNCOMMON PROBLEM WITH THESE SWITCHES. (TC NR0 20060509002)