What was found
ON MY 20TH THE FLIGHT CREW WAS ON APPROCH AND SELECTED GEAR HANDLE DOWN , GEAR EXTENDED WITH NO INDICATION OF BEING DOWN AND LOCKED , CYCLED GEAR AGAIN WITH NO INDICATION, AGAIN CREW COULD HERE GEAR EXTEND BUT STILL NO INDICATION . FOLLOWED QRH PROCEDURES AND STILL NO INDICATION OF DOWN AND LOCKED . CREW DID A TOWER FLYBY AND WAS TOLD GEAR WAS DOWN , SO ON FINAL THE PIC NOTICED THAT THE INSTRUMENT LIGHTS SWITCH WAS IN DIM , SELECTED BRIGHT AND ALL 3 LANDING GEAR LIGHTS CAME ON AS NORMAL, DURING DAY LIGHT IF DIMMER IS SELECTED IT IS DIFFICULT TO SEE LIGHTS, NO MECHANICAL IS WAS PRESENT