What does 'in good working order' mean in contract law?

[Cattlegod]

If I lease something and it says that it must be returned 'in good working order' -- what exactly does the 'good' part mean? I understand working order - either it works or it doesn't, but what about 'good working order'?

Any ideas/thoughts?

 

[joebloggs10]

It functions properly, it's not broken, it's not jury-rigged, it doesn't require any special (non-manufacturer) tools or procedure to operate.