Once the big nut is removed, the axle may not want to come out. Nothing is
holding it in, though. Smack the threaded end(with the big nut screwed on a
few turns)and the stub axle will pop out. Some kind of suction is holding it
in, and rather tightly, too.

Use great care when adding grease. Leave lots of room for grease expansion
or a seal will blow. What a mess!