Stuck Casters? HOWTO Clean and grease caster wheel bearings

I found this rolling cabinet on the side of the road on trash day and though "Yes, I could use a set of casters!". When I got it home and tried to roll it around, it felt like two of the wheels were locked, even though the locks were disengaged! A liberal sprayout with WD-40 and adding grease (I couldn't find any evidence that they had grease originally) restored them to very good condition.