For five weeks, Michael "Mac" Ling had been at the Lexington, Virginia, plant of Darden Motor Works (DMW), interviewing production supervisors, quality experts, maintenance supervisors, and repair personnel. He was investigating a puzzling problem: how dirt was infiltrating the paint on trucks assembled at the facility--and how to stop it. Small particles were causing a big, and expensive, problem. Nearly one out of three trucks had to be reworked owing to dirty paint, at a cost of a few dollars to a few hundred dollars per vehicle. The student must develop some hypotheses regarding the causes of the problems.