This qualitative research examines the cognitive processes embedded in self-explanations of automobile and motorcycle service technicians performing troubleshooting tasks and solving technical problems. In-depth interviews were conducted with twelve service technicians who have obtained the designation of "master technician" or equivalent within their work environment. Cognitive processes revealed include: self-talk, visualization, linear and hierarchical thinking, use of job-aids, rule application, and the learning incidences that occur through social contact. Implications for training are discussed.