Check them ouot and see if they have grease fittings or fitting plugs
If they have grease fittings just grease the beast
If they have the fitting plugs (looks like a 6-8mm bolt) in the bottom of the ball joint, take them out and install grease fittings, then grease the beast
While you are there check the play in the ball joint, if it isn't to spec after greasing, replace.
If it doesn't have etheir...gotta replace the balljoint
Zag