How should excessive looseness in kingpins be addressed?

Excessive looseness in kingpins indicates that there is a significant wear or damage present in the kingpins or their bushings, which can affect the steering and stability of the vehicle. In such cases, the most effective solution is to replace the kingpins and bushings. This is because merely lubricating or adjusting them may not restore their proper function or address the underlying wear.

Replacing both the kingpins and bushings ensures that the components will properly fit and function together as designed, thereby restoring the integrity of the steering system. It is crucial to address the issue comprehensively rather than attempting temporary fixes, as a failure to do so could lead to further vehicle handling problems and potential safety hazards.

The other choices are less effective because they either do not adequately address the problem or provide only temporary relief. For instance, lubrication may help if the issue were simply one of dryness, but it will not resolve problems related to wear. Adjusting may correct minor alignment issues, but it does not fix the root cause of excessive looseness. Tightening the steering linkage could improve steering feel, but it wouldn't resolve the actual kingpin wear issue leading to looseness.