Just finishing up my JD. My first later model job. Black soot everywhere. Thought I would have a problem putting it back together, but it was almost easier than taking it apart. Here's some photos online (not mine).

http://crinear.smugmug.com/Pinball/Judge-Dredd-teardown/13512243_7M8HQL#984370727_ct7r2

Yes, it was pretty easy. I think I just removed a few screws and wiggled it out from under the wiring. It was the dirtiest part on mine also. One problem was trying not to track the soot that was on everything onto the bare wood under the playfield.

As I don't have much room to work, I worked on the playfield in the cabinet. I first removed and cleaned/rebuilt the parts/pieces underneath the playfield one at a time (except deadworld). I then removed the parts on the lower half of the upper playfield, cleaned and reinstalled them and then did the same for the upper half of the playfield (I did deadworld at this time). I thought I would have a problem figuring out where the parts went for re-assembly, but it wasn't as bad as I expected. I kept screws with their respective parts and kept track of what post/support went where.

I use alcohol to get the dirt off of most everything (but not paper labels). I use marine polish on the plastics and metal. I re-grained the metal by hand with 100 - 120 grit sandpaper and finished off with marine polish. That was enough work that I will look at getting some kind of abrasive wheel if I do that much metal again.