But only if you're still running stock hubs. If yours have been changed out to aftermarket, such as Warn, the spring and cup are deleted completely.
Usually a reason for them being fubared in the first place, is when they get left in after installing aftermarket locking hubs.
You're not talking about the thick washer with all the holes in it though, are you?
That's the lock-ring that goes between the inner adjusting nut (the one with the little pin pointed outward) and the outer locking nut.
And while Kyle's adjustment procedure has worked fine for him for many years if I remember, the "official" adjustment procedure is as follows:
1. Torque inner nut to 50 ft/lbs while spinning the wheel/hub
2. Back off 1/4 turn. (and don't worry about the preload being so loose)
3. Install locking ring with it's tab in the groove on the spindle so that pin on inner nut aligns with a hole. If it doesn't line up perfectly the first time, flip the ring over to see if it will line up then. If not, you can slip a finger behind it to turn the nut until the pin lines up. A very little bit of turning is all that's needed.
4. Torque outer nut to 75-105 ft/lbs.
Paul