What was found
(CAN) ON APPROACH, PILOT SELECTED GEAR DOWN AND DID NOT GET NOSE DOWNLOCK INDICATION. ACFT RETURNED TO DEPARTURE AND RECYCLED LANDING GEAR DOWN, STILL DID NOT GET DOWNLOCK INDICATION. CREW ALERTED ATC AND PROCEEDED WITH EMERGENCY GEAR DOWN PROCEDURES. STILL DID NOT GET DOWNLOCK INDICATION. ACFT PERFORMED UNEVENTFUL LANDING. MX JACKED ACFT AND PERFORMED GEAR SWING. TROUBLESHOT PROBLEM TO FAILED NLG DOWNLOCK SWITCH. SWITCH TURNED OFF HYD BUT DID NOT GIVE DOWNLOCK INDICATION. NLG DOWNLOCK SWITCH REPLACED.