Mike, could you please explain to me how 2-stroke got on the other side of the carb? I'm very interested in that. Although I''ve never experienced that problem on my KTM, I wanna be ready for when it does.
Redrider has your best advise birg, I also like Spectro cleaner and oil. Dab the cleaner dry before oiling, and I like to let the filter dry a bit after oiling. Take time to put a bead of grease or window sealant around the rim of the filter to insure you have no leaks.
Now that I think of it, the oil does seem like it's two srtoke oil, I don't soak the filter but I'll try hanging it over night. This does not affect how the bike runs so I'm not worried. But how would two stroke oil get on that side of the carb? That would be someting.
It is the overflow from your gearbox draining into your airbox. I find oil in my airbox if I have crashed the bike upside down, put in too much oil, lay it down to move a log etc. Good way to keep the oil off the trail IMO.