I have found that removing them is the best way to cure that.
On the knuckles trunnions I support the axe under the lower arm and pull the top bolt out ( mark it first to show where it must go when reinstalling it).Tip the knuckle out and unscrew the threaded sleeve. Give it a good clean and grease it before reinstalling it . It must have clearance so it will feel loose. You can only check these by putting a straight edge on the threads. Any low spots indicates wear.
You can do the bottom sleeve at the same time but in both cases you remember that the sleeves are the fine adjustment for the caster so count the number of times you turn them when removing them.

If you are worried about spring tension, do as I do it, put a spring compressor on the bottom arm lip and the other end on the top arms lip and use it to keep the spring compressed. It makes it easier to pull the king pins etc.
I do this when I am assembling a front end on the bench or in a car with no engine.