"Yes," Curtis replied. "You should have."
Noah took the envelope from his jacket and handed over the entire purchase price. He offered to cover the reasonable expense of the failed installation from what remained of his savings, and he helped arrange for the engine to be removed safely with the mechanic's assistance. Curtis accepted the refund and agreed on the actual costs after seeing that Noah was not trying to evade them. The money Noah had imagined putting into new tools disappeared almost as quickly as it had arrived.
On the drive home, Rachel kept both hands on the steering wheel. The rain had stopped, leaving the road glossy under passing headlights, and the cab smelled faintly of damp denim and old coffee. Noah held the engine's specification sheet on his lap. He read the same numbers over and over, as though one more reading might make them say something different.
"You made a mistake," Rachel said at last.
"I know."
"Are you going to make another one trying to pretend it didn't happen?"
"No."
"Then don't spend all night punishing yourself. Write down what went wrong. Learn what you need to learn. Tomorrow you'll still have fifteen other engines to investigate and one returned engine to understand better."
Back at the workshop, Noah helped Ellis unload the returned machine onto a stable support. He wiped moisture from its surfaces, tagged it as unsuitable for the previous application, and placed the original sales receipt in a new file marked RETURNED. Then he did something he had not done since the auction: he sat in Earl's chair without opening a tool drawer. The shop sounded emptier than it had before the engines arrived.
He counted his remaining cash. Between the auction purchase, transport, materials, refunds, and installation expenses, his savings were close to gone. He still owned sixteen engines, but one had just taught him how little the word owned could mean when no one had a reason to trust what he said about them. He considered asking Ellis to help him load everything back onto a trailer and carry it to the scrap dealer before he lost even more.
Noah imagined the faces at the auction if they heard the news. The manager would laugh, the farmers would say they had warned him, and Carter Dunn would have a new joke by the next morning. None of that would hurt as much as the expression on Curtis Hale's face when he had stood beside his stalled equipment. Noah could tolerate being laughed at. It was harder to know that someone had relied on his judgment and been let down.
Near midnight he opened Earl's green notebook. He was not looking for a clever trick or a forgotten specification that would prove he had been right after all. He wanted, without knowing exactly how to ask for it, to hear his grandfather tell him what to do when the machine he had repaired was not the thing that needed fixing. His thumb settled on a page bearing a rough sketch of a generator drive and a note written in Earl's steady hand.