What was found
DURING GEAR RETRACTION, CREW HEARD A LOUD THUMP FROM NOSE GEAR AND RECEIVED A "LG WOW SYS FAIL EICAS" MESSAGE. EXECUTED QRH. AIR RETURN. DURING LANDING GEAR EXTENSION, GEAR CAME DOWN NORMALLY AND THE EICAS MESSAGE WENT AWAY. LANDING GEAR, BRAKING, AND STEERING SYS ALL WORKED PROPERLY. PERFORMED NLG SHOCK STRUT SEAL REMOVAL & REPLACEMENT. PERFORMED ACFT JACKING PROCEDURE & NLG SHOCK STRUT SERVICING, NLG EXTENSION AND RETRACTION NORMAL AND OPS CHECKED GOOD IAW AMM 32-21-04, 07-10-01, 12-12-09.