What was found
CLIMBING THROUGH FLIGHT LEVEL 380 UP TO FLIGHT LEVEL 430 WE ENCOUNTERED SOME HEAVY VIBRATIONS COMING FROM THE NOSE SECTION FOR ABOUT 10 SECONDS. ABOUT FIVE MINUTES LATER THE GEAR DISAGREE N CAS MESSAGE APPEARED ALONG WITH A AMBER CROSSHATCHED SQUARE ON THE NOSE GEAR SYNAPTIC. THIS STAYED ON FOR APPROXIMATELY 30 MINUTES, THEN WE FELT A SMALL VIBRATION AND THE NOSE GEAR INDICATED UP AND THE CAST MESSAGE DISAPPEARED. NO OTHER ABNORMAL INDICATIONS AFTER THAT. FOUND NLG SWITCH OUT OF RIG AND CONTAMINATED. REMOVED NLG SWITCH AND INSTALLED CUSTOMER SUPPLIED NEW NLG SWITCH, ADJUSTMENT GOOD. OPS CHECKS GOOD IAW AMM 32-32-25.