How do you earn your living?

This topic has come up a lot in the past 6 months. I enjoyed this article, and plan to buy the book when it comes out.

Here's an excerpt from the article:

There is always a risk of introducing new complications when working on old motorcycles, and this enters the diagnostic logic. Measured in likelihood of screw-ups, the cost is not identical for all avenues of inquiry when deciding which hypothesis to pursue. Imagine you’re trying to figure out why a bike won’t start. The fasteners holding the engine covers on 1970s-era Hondas are Phillips head, and they are almost always rounded out and corroded. Do you really want to check the condition of the starter clutch if each of eight screws will need to be drilled out and extracted, risking damage to the engine case? Such impediments have to be taken into account. The attractiveness of any hypothesis is determined in part by physical circumstances that have no logical connection to the diagnostic problem at hand. The mechanic’s proper response to the situation cannot be anticipated by a set of rules or algorithms.

That's a complicated way of saying that sometimes you have to solve hard problems, and those hard problems involve both working with your head as well as your hands.