First thing to do is locate the NSS of course. It's down on the passenger-side of the tranny. Not the easiest location to work on, but all you really have to do under the rig is get the NSS off the tranny...

Now that you've found the NSS, you'll need to remove the 12mm bolt from the top of the switch case, then pry down the tabs on the lock washer and remove the large nut from the switch case.

Next you'll need to pull the NSS off the tranny. It's rather stubborn, and you can't 'twist' it off -- it's got to come straight off. Using a great tip I got from the JeepsUnlimited Cherokee forum, I threaded the retainer nut back on a couple of turns, then used a flat head screw driver to carefully pry the NSS off, using the lip of the tranny pan for leverage. This worked like a champ and didn't damage the unit.

Now you'll need to go unplug the NSS from the engine bay. The plug is located to the side of the valve cover by the dipstick. The harness will probably be held in by a couple of zipties, this was actually the hardest part of the process -- snaking my hand up behind the engine to cut the zipties. One thing I found handy was to tie a length of wire to the plug, so that when I pulled it down and out of the engine bay, I threaded the wire down with it. This will help out later when you need to get that plug back up into the engine bay from below.

This is what the NSS and its harness looks like.

Now that the switch is out of the vehicle, it's time to take it apart and clean it. There are 6 small Phillips-head screws holding the switch case together. Once you remove these screws you can pull the two halves apart.

With the switch disassembled, clean out both halves with carb cleaner or something similar. I used brake cleaner. Be careful removing the wiper arm, there are two small spring-loaded brass contacts that may fall out, and they're hard to find if they do... On mine, one of these contacts had gotten stuck up in the wiper arm due to the dried out grease inside the switch.

Once everything is nice and clean, take some very fine sand paper and polish the terminals on the switch half as well as the contacts in the wiper arm.

Now grease the switch parts with some white lithium or dielectric grease and reassemble the switch.

Place the switch back on the shaft on the tranny and replace the lock washer, retainer nut, and locating bolt. Here's where the wire we threaded down earlier comes into play... the NSS's plug needs to go back up into the engine bay. The the end if the wire around the plug and haul it up. Plug the harness back in!