Either or both of the upper and lower swivels may have grease nipples; ball joints have them on the housing.
Wipe the nipples clean and see if there is still grease in the orifice. If not, the joint has become dry, so take extra care to grease it thoroughly.
Get a helper to move the steering wheel slowly from lock to lock while you inject grease with a grease gun. This will help circulate the lubricant. Do not swing the steering violently on rack-and-pinion systems when the wheels are off the ground. The sudden pressure surge inside the rack housing may damage the rack gaiters.
See that the gun is filled with grease of the correct grade, and inject each nipple until fresh grease exudes from the joint. Wipe the nipple clean. Do not over-grease a ball joint; the rubber seal round the top of the joint can easily be forced out by excess pressure from a grease gun.
Be sure to grease all the nipples.
Some cars, such as Triumph, Datsun and Toyota, have blanking plugs instead of nipples.
Clean the area around the plug thoroughly with a wire brush and absorbent rag before removing it.
Screw in a nipple, making sure that it goes fully home, otherwise grease may exude back along the threads.
Inject grease with a high-pressure grease gun, then remove the nipple and replace the blanking plug.