Don't let the length of this post scare you, it's just several solutions by different riders.
The Neutral Sending Unit screws have been known to loosen themselves and find their way into the tranny gears, not good. Does not seem to be related to model year or mileage. It's a small percentage failure number, but a big disaster $$$ if it happens. After removing the clutch cover: remove, clean screw threads and holes, then Loctite or safety wire. I prefer safety wire.
So if your neutral indicator light quits or starts acting funny......
"One point though on the screw just gently falling out and settling on the bottom. The hurricane turbulence of the clutch basket and gears
in the oil can easily sweep the screw up into places that would be a major bummer for it/them to be."
Like these two pics:
Thanks to LukasM, pics are worth a thousand words:
Mine only has the single blue wire:
2laneblacktop's step by step and NSU screw sizes
The two NSU screws, the pin and spring hiding behind the NSU, looking to escape:
TREE posted this, I think a good solution:
This is the plan for my NSU bolts . . . easy to wrench and then they will be lockwired.
plodalong posted his idea:
The oil pump drive gear is some sort of resin/fiber construction, so I replaced it (at 15,000 miles). It's $19.94 and #7 here:
There is also a seal in the clutch cover I'd replace while in there. It's shown in the middle photo on page 3-42 in the service manual.
It's on the crankshaft page, #10 here: