He touched the contact area with a fingernail and brought away a trace of oxidized material. He remembered Thomas showing him a similar fault on an old delivery van, explaining that electricity did not care whether a bolt looked properly tightened. It cared whether the actual surfaces could conduct. A mechanic who assumed contact because two pieces of metal were touching might replace every good part connected to them before discovering the simplest break in the circuit.
Curtis Wade bent forward, looking down from the edge of the crowd. He had measured the battery and wiring but had not accounted for resistance at the hidden frame contact. In his mind the diagnosis he had given Garrett was rearranging itself, not completely disproven in every detail, but shaken at its foundation. He understood suddenly that the boy was working from a different kind of evidence and that his own elaborate instrument setup had hidden as much as it revealed.
Owen loosened the contact enough to clean the mating surfaces. The folded emery cloth from his pocket removed the thin discoloration with short, careful strokes. He cleaned both sides rather than polishing only what could be seen from below. Then he reseated the strap, tightened the fastener, and checked that the connection would not shift under vibration.
"Ground was corroded," he said. "It had enough contact to look fine. Not enough to give her a reliable spark when the other two faults started stacking up."
He slid out from beneath the frame. Somebody in the crowd whispered that he had sounded exactly like a teacher. Owen rose without noticing, brushed grit from his shoulder, and began closing his toolbox. He did not want the crowd near his father's tools when the engine started, and he had learned to leave a work area safe before declaring any job finished.
The timer showed less than a minute. Three repairs had been made, but the wager was not to name three problems or impress Eleanor Graves. The wager was to make the bike run. There was still the possibility that some fourth fault existed, that the engine would turn and remain dead, and that every person who had mocked Owen would claim the result confirmed what they had believed all along.
Owen looked at Garrett. "Try it now."
For the first time in three days, Garrett seemed uncertain about approaching his own motorcycle. He stared at the boy, then at the black tank he had polished for decades. His hands were big and strong and marked by old injuries, yet they hovered near the handlebars as though he had forgotten how to use them. If the engine did not start, he could still retain the public advantage. If it did, the only defense left to him would be to deny the evidence everyone had seen.