There is a hole (drain hole?) in the swing arm of the touring bikes right above the plastic (on my RK) belt guard. There's a couple of small screws holding the guard. Drop the belt guard and you can see the drain hole in the swing arm but no hole in the belt guard. Some guys have taken their bikes to the dealer to fix this. If you ride in a lot of rain, the swing arm can get water into it from a hole in the front of the swing arm. Apparently water gets in through the front hole and can't drain out very well as the guard is pretty tight against the drain hole. But after a while rust develops and then dribbles on the floor beneath the bike.
It never rains here in So Cal so I looked at mine and no rust. But to be pro-active I drilled a small tapered hole in the plastic belt guard where the drain hole is. Tapered so the hole next to the frame is larger than the hole where it exits the guard ~1/16". Water could get in there from the belt if the hole is too large IMHO.
I could've taken it to the dealer for the fix but those guys are not as careful as I am and I didn't want them to just drill a hole through both the guard and the swing arm. Not saying they would do that, I just didn't want to chance it. Years ago my wife bought me a real 'spensive racing bicycle. The moron at the bike shop talked her into adding a kick stand????? on a racing bike????? anyway, he crushed the left lower frame tube and when I brought it back to show him, he couldn't figure out what the big deal was. It's tough to find craftsmen any more.