I know that the Tiger Cat is the same. You need to remove the plug (bolt), part number 482028-01, and install a grease zerk in order to grease the caster wheel pivot. The zerk fittings cost less than $1.00 each. If Scag does not install them for fear that they will be broken off during everyday use, why don't they give you one or two of them in a bag with the manuals?
The question I have is do you have to remove the grease cap 481559 before greasing and if so what is the best way to remove it? The Tiger Cat manual mentions using a special Scag tool 47007 for the installation but nothing for the removal. It looks like a large socket placed over the grease cap would work fine for the installation though.