Imagine you are holding either end of the cross member in your hands
If both hands can go back & forth, that is normal
If one hand goes u & the other goes down this is normal
if your wrists twist while this is happening then this is wear
If one hand goes foreward while the other goes back that also is wear
Because of the slope in the king pin the upper & lower plastic bushes do wear so require replacement as do the wheel bushes.