Grease will reduce the effectiveness of this system...even oil or
any lube
The trunnon end has a bent depression that the cam rests in
When the trailer sways off center line...there is resistance to that
side movement via the cam in the depression. Both tronnon bar ends
One will resist with a 'pull' and the other will resist with a 'push'
When it sways enough to pull/push the cam out of that depression...the
cam will 'lift' the trunnion out of the depression to increase the
spring tension on the hitch head
That is the 'noise' of this type if WD Hitch system
Just noodle why the OP's cam is worn....it is doing it's job by
resisting side to side movement
Greasing it will reduce it's resistance to side to side movement
and lose some of it's anti-sway forces
Here are a couple images that might help visualize this
eTrailer.com and click on the image with the force vectors
Here is a static image of that force vector diagram
Notice how they show the spring bar end with the cam out of that
depression because the trailer is way off center line
