I squatted down in the dirt and took stock of my inadequate tools. Over my left shoulder a massive John Deere tractor loomed. I came here to fix that tractor. So far, things weren’t going as planned.

Hands up who knows the difference between a tractor’s rated and maximum power? Or what the perfect torque curve should look like? How about torque rise? Or six-point fuel tests? If this mumbo-jumbo ...