"A mechanic."
At noon, Eleanor returned alone.
She found Isaac washing his hands in the deep steel sink near the rear wall. Raymond's truck was idling outside, exhaust steady, no ticking from the manifold. Raymond himself stood beside it listening with the expression of someone who had already decided the engine sounded like his brother again.
"What do I owe you?" he asked.
Isaac dried his hands. "Two hundred eighty-seven."
Raymond stared. "The other place said twenty-eight hundred."
"They were replacing parts I repaired."
"You're bad at business."
"Been told."
Raymond counted out cash, stopped, then put another twenty on the counter.
Isaac pushed it back.
"Coffee fund," Raymond said.
"Coffee's terrible."
"Then buy better coffee."
He drove away before Isaac could return it.
Eleanor watched the truck turn onto Route 12.
"You don't quote prices in advance?"
"I quote when I know what failed."
"That is a dangerous business model."
"So is building things to a schedule before you know what fails."
The sentence landed between them without decoration.
Eleanor did not defend anyone.
She opened the folder again on the workbench.
"The ninety-three-minute pattern was identified by one of my analysts. Nobody could explain the mechanism."
Isaac looked at the traces.
"It's resonant coupling."
"Between what?"
"The thermal transition and the valve housing. Your design teams modeled thermal stress and vibration separately."
"They did."
"That's the problem."
He took a pencil from behind his ear and pulled a clean sheet of brown packing paper from beneath a parts invoice.
"Every orbit, the vehicle moves between heating and shadow. The material expands and contracts. That's not enough to break the regulator by itself. The housing also has a natural vibration band. That's not enough by itself either. But when the thermal cycle shifts the stiffness just enough, you cross a resonance condition for a short part of every orbit."
Eleanor watched him draw two curves, then a third crossing them.
"The assembly starts feeding energy into its own weak point," he continued. "Not all the time. Just long enough, over and over. That's why ground testing missed it. You tested the stresses. You didn't test the relationship."
"Can you prove that from the telemetry?"
"If I'm right, there'll be a secondary harmonic at about one third the main cycle interval. Not exact because the system isn't ideal. Somewhere around thirty-one minutes."
Eleanor already had her secure tablet open.
She scrolled, filtered, enlarged a data series, and stopped.
"Thirty-one point two."
Isaac nodded once.
She looked at him differently after that.
Not dramatically. No sudden awe. No cinematic pause.
It was a recalibration, the professional kind. She had arrived believing she might need a dismissed engineer's memory. She now understood she needed the engineer himself.
"Can it be fixed in software?" she asked.
Isaac did not answer immediately.
He stared at the paper, drew another set of lines, and crossed one out.
"Maybe."
"Maybe is better than what I had this morning."
"Don't get attached to it."
"I don't get attached to maybes."
"Good."
He set the pencil down.
"If we're going to do this, I need live data, the current valve command profile, the actual environmental history, and the engineering change records from the propulsion assembly. Not the summaries. The raw revisions."
"Some of that is classified."