What was found
GEAR DISAGREE WARNING SHORTLY AFTER GEAR SELECTED UP FOLLOWED BY NOSE DOOR WARNING MESSAGE. THE NOSE GEAR WAS STILL SHOWING DOWN AND LOCKED. COMPLIED WITH QRH FOR GEAR DISAGREE UNTIL MANUAL RELEASE HANDLE STEP. BOTH HYDRAULIC 3B AND 2B PUMPS SELECTED ON. MESSAGES DID NOT CLEAR. THEN COMPLIED WITH QRH FOR NOSE DOOR BY SELECTING GEAR DOWN. THE MAIN GEAR CAME DOWN AND BOTH MESSAGES CLEARED. ALL THREE GEAR SHOWED DOWN AND LOCKED. DIVERTED TO RAP. (FLT 5101) CLOSED ICE BUILDUP ON NLG OLEO CENTERED/EXTENDED SENSOR CAUSED A FAR CONDITION IAW FIM. ADJUSTED SENSOR PS14GA IAW AMM. PERFORMED MULTIPLE GEAR SWINGS IAW AMM, NO FAULTS FOUND.