Involves taking the entire rotor out, bearings, and axle shafts. The seals keep the differential fluid from leaving and coming out of the axle tubes. Make sure you don't have too much fluid in there. Another possibility is the vent is stopped up. If the vent is stopped up pressure will build up and come out at the least resistance.
YOU ONLY NEED TWO TOOLS IN LIFE - WD-40 AND DUCT TAPE. IF IT DOESN'T MOVE AND SHOULD, USE THE WD-40. IF IT SHOULDN'T MOVE AND DOES, USE THE DUCT TAPE.
IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.