it'll be ok as long as it hasn't worn through the hardern'd surface of the ball bearings

if you get away with a regrease and job done then it's easy, but if you want to strip it down to inspect it, the balls will have a bit of a shine on them a different colour to the rest of the surface, this is what will be causing the clicking as it's now not properly round and it's catching on he worn part of the surface of the ball