Soak it in a solvent like diesel fuel or mineral spirits, then when it's free, spray it full of white lithium aerosol grease. This stuff will require several applications as it goes on thin, then dries but loses volume. The grease injector would overcome this difficulty but your shop may not have one.

It is definitely very important to get grease in there because it's what stops the fw from getting full of grit as well as providing lubrication.