There were few directions with it other than the usual oiling of
the rollers for maintenance, but my main question is how to get the
gunk cleaned off it as the whole thing seems to be packed in
petroleum jelly. What do I use to get this cleaned up and the unit
ready for use?
It sounds like the rolls are covered in cosmolene, a petroleum based
substance used to prevent rust & corrosion of ferrous metal while in
shipment & storage.
The best way to get it off is to wipe off as much as you can with
rags or paper towels. Then use kerosene or paint thinner on an old
paint brush or rags to remove the rest.
The other option is to ask someone who’s been in the military,
they’ve probably had to clean a lot of cosmolene from stuff (bg).