I've Cleaned them before, when I had a starting issue, didn't know they affected the back up lights too.
Now to figure out my fuel guage.
Plenty of tips in dealing with the AW4 NSS - just
be careful removing it! I've posted images of a tool that will be quite useful, it's called a "cast spreader," and it's a medical tool. You can usually find it on eBay for $25-30, and it will get useful for quite a few other things once you get it and see how it works. And, it helps keep you from breaking the NSS housing.
Remove the switch, disassemble it (be careful - the screws tend to seize!) and open it up in a bag that's big enough for both hands to fit in (there are small spring-loaded parts inside.)
Scrub all the bits with a toothbrush and contact cleaner solvent. You may also use denatured alcohol for this - it breaks up the crud and won't leave residue. Dunk the parts to rinse them when they're clean.
Lightly lubricate internals with corrosion inhibitor.
Very lightly. You just want enough to help the internals move freely.
Lighty coat one of the mating surfaces of the housing with RTV black. You don't want so much that it squidges out into the housing, but it will help keep the internals clean.
Use either RTV or LocTite #222 on the screws that hold the case halves together. Tighten to finger-tight plus about 1/6- to 1/4-turn. (Too tight, and the switch will bind.)
Use a wire wheel to clean the shift shaft, paint it with never-seez.
Install the switch.
Tighten the collet nut to 5 pound-feet, you don't need to use anything (can't hurt, but you don't need it.)
After you adjust the switch, the adjuster screw gets tightened to 15 pound-feet. I do suggest using RTV on the adjuster screw - that way, you don't need to pull it out and recoat it if/when you adjust the switch in the future. I've given a procedure for adjusting the NSS in detail on various boards, including this one I'm sure.