The greasing is in the owners manual but being a HD return you may not have got it. Actually the book says to just remove the wheel and squirt some oil on the edges of the pinion for it to seap under but its better to remove it and grease as done from the factory.

Its funny, about half of the Toro drive problems are related to the pinions getting dry and sticking and this includes all the other models with zerks for this purpose.
LMRM; Bob