The trainees are taking their passenger test. If they pass, they'll be able to carry passengers all on their own. Brewster and Wilson are a little nervous, but Koko is confident - after all, she's a passenger train! Mr. Simkins, from the Ministry of Chuggers, arrives to examine them. His 'jiggleometer' will tell him whether or not the trainees are riding smoothly. Koko volunteers to go first. Unfo...