Rob Dirts picture a few posts before this is great. As others have stated, you do not need to remove the tank in order to get to it. What I did notice on mine though is I could spray the outside, above, below the rubber boot all day long and I got no positive results. All the sliding surfaces are actually hidden UNDER the rubber boot. I did all my work from the right side of the bike. I took a long flat screwdriver and pushed UP the boot just enough to get a long nozzle (taken off my chain lube can) on my WD40 can up under the boot. One small shot of WD40 is all it takes. Then I took my time with that same screwdriver to get the boot slide back down over the housing like it was.
Also, mine did not start acting up until about 16,000 miles and mine has only been used slightly off road. It did not look dirty under the boot so I'd assume it just dried out under there.
2015 Tiger 800 XCx