...I encourage folks not to be intimidated and do the job per factory rather than sling seeping oil all over their rear wheel.
Here's a Nexus-8 after rinsing the gear cluster in mineral spirits and reassembling it. The "C" clip on the axle comes off (careful! It likes to fly away!), then the bulk of the gears come off as a unit.
I was having an occasional "crunching" sensation in this hub, which has over 12,000 miles on it. After the rinse in mineral spirits, I found several small bits of metal in the sludge at the bottom of the jar. These were able to be picked up with a magnet. After reassembling the hub, it was dipped in gear oil (75w-140), drained then reinstalled. The bearings were lubricated with Nexus grease. The hub now performs perfectly.
The gear cluster after cleaning and reassembly. Use caution removing and replacing the circlip that holds the cluster on the axle... it likes to escape.
The reassembled cluster immersed in the gear oil.
For some reason, the black plastic cap that covers the drive-side bearing keeps coming loose. An easy fix is a few zip-ties. No leaks here! (Sprocket is due for replacement.)
Another view of the zip ties holding the cover in place.