Keep in mind that hosing the freehub down with WD will maybe make it work but it'll certianly also wash out most of the grease from the DS wheel bearing. So use the WD treatment only as a way to evaluate the need to buy a new freehub. If it does and runs smooth then fine, you only need to flush and oil it. But you'll still need to pull the axle apart so you can clean and re-grease the wheel bearings.
Also to get to where you have a spot to squirt the WD into the freehub you'll need to remove the cassette and the little dust shield that is just under the cassette lockring. Once you're in that far you'll see the wheel bearings staring at you. The slot between the outer freehub shell and the non rotating bearing cup is where you want to squirt in the WD.
None of it should be scary. It's all just about doing one easy little job at a time. It's only scarey if you look at the list all at once.....
