What was found
(CAN) DURING APPROACH, THE CREW WERE UNABLE TO GET A 'DOWN AND LOCKED GREEN LIGHT' ON THE NOSE GEAR. THEY CYCLED THE GEAR SEVERALTIMES AS WELL AS TRYING THE HAND PUMP. INVESTIGATION REVEALED AN INTERMITTENT CIRCUIT IN THE 'DOWN AND LOCKED' CLOSED SIDE OF THE SWITCH, WHICH PREVENTED PROPER INDICATION. INDICATIONS ARE THAT THE ORIGINAL SWITCH INSTALLED IN THE AIRCRAFT, AND HAD NEVER BEEN CHANGED.