What was found
AFTER SELECTING LANDING GEAR UP DURING TAKEOFF, NOSE GEAR REMAINED DOWN FOR APPROXIMATELY 15 TO 20 SECONDS. GEAR DISAGREE N CAS MESSAGE + A SECOND AMBER CAS MSG DISPLAYED (DO NOT RECALL WHICH MSG SPECIFICALLY). AFTER 20SEC, NOSE GEAR CAME UP AND CAS MSG WAS GONE. CORRECTIVE ACTION: REMOVED SUSPECTED FAULTY NLG UPLOCK SWITCH AND REPLACED WITH CUSTOMER SUPPLJED NEW UPLOCK SWITCH REF: AMM 32-32-00, PERFORMED MULITPLE OPS CHECKS WITH NO DEFCTS NOTED. ADVISED MCC OF FINDINGS AND MCC REQUESTED MAKE SURE NLG IS CENTERING COMPLETELY AND ALSO TO CHECK THE RIGGING ON THE UPLOCK ACTUATOR. IAW AMM 32-32-00.