Stifling a yawn, Gus shoved his ledger aside and went out to the shop. Seeing the pinched, sour face of the man waiting in the '59 Buick there, Gus scowled. Stan, Gus's helper, hastily lost himself under a car hood.

"Hello, Silas," said Gus without enthusiasm. "How's your bargain car doing?"

"Nothin' wrong with it!" retorted Silas Barnstable, the stingiest man in town and easily Gus's worst customer. "I'm here to make you a deal."

Gus sighed inwardly. "What kind?"

"Remember them agency fellers that kept filling the differential too full, so it leaked on my garage floor? Well, a month ago I found where it was comin' out. Stopped it, too, by dab!"

"Well, bully for you," returned Gus.

"No call to get sassy," said Barnstable indignantly. Then he turned on what he thought was an ingratiating smile. "Been wanting to check the grease again, but I get cricks crawling under. Thought maybe I could put the car on your rack a couple of minutes. Now, here's the deal. If it needs grease, I'll buy it from you. Hold on -- " Silas hastened on as Gus opened his mouth. "It won't cost you nothin', and I already done you a favor."

"I was going to say okay, since the rack isn't in use," Gus replied. "But if you did me a favor, I'd better check it out."

Barnstable's Adam's apple joggled. "Tryin' to tell you, ain't I?  Went out to look at some prop'ty this mornin' and stopped for some stuff at the Route 9 shoppin' center on the way back. There was this furrin-looking car coughin' and bangin' in the parking lot, so I asked the driver if he wanted a tow cheap, bein' as how I was right there anyway.

"The young feller talked kinda funny, like maybe he was a furriner, too. He said he had some spare plugs he'd try. Time's money, so I didn't wait. But I told him if it don't run right to come here, 'cause you wouldn't charge him no worse'n most garages, and 'd do a lot better job."

"Thanks a lot," said Gus dryly. "Okay. Put your car on the rack."

Gus watched the car until it was safely in position, then headed back to his office, yawning. At the door he stopped, struck by a thought that he now realized had been gnawing at him for minutes.

Turning, he saw that Silas was unscrewing the grease plug in the differential housing. Gus ran toward him.

"Hey, Silas! Hold it," he warned. "How did you stop -- "

With a small explosive pop, the plug flew from its hole and struck Barnstable on the forehead. A spurt of viscous black grease followed.

Silas yelped and sprang back. Under the car hood, Stan had heard Gus's cry. He'd looked up in time to see the whole thing and was overcome by an uncontrollable fit of choking.

Wordlessly Gus handed Silas a rag.

"I'll sue!" Silas sputtered as soon as his face was free of grease. "I'll charge you with malicious mischief and causin' personal injury, Gus Wilson!"

Gus made no answer.

"You knew that would happen!" raged Barnstable. "You yelled, to take my mind off what I was doin' and -- "

"I tried to stop you," retorted Gus. He walked under the car and inspected the rear-axle housing. "Come here, Stan. I want you for a witness."

Silas, still fuming, watched with Stan as Gus pointed to a small plug set in at the top of the housing. "That's a pipe plug. But on this car there should be an open vent line here, to release the pressure built up as working parts warm up in operation.

"Because it oozed grease, Silas took off the vent line and screwed in this plug. It bottled up the pressure, probably forced some grease past the bearing seals, and blew up in his face just now. Still want to sue, Silas?"

"A lawyer'd cost me more than I'd get. I'll forget it if you put back that vent thing. I never threw it away. It's in the trunk."

"Maybe it was my fault at that," mused Gus after Silas had driven out.

"Aw, how could it be, Gus?" asked Stan.

"If I'd been wide awake, I'd have caught on as soon as he said he'd stopped that 'leak.' But I watched a late TV movie last night and I'm sleepy."

"Well, I wouldn't bother feeling sorry for pinch-penny Silas," returned Stan. "Nor believe that fairy tale about sending you a customer either."

The phone rang. Stan answered it and came back looking confused.

"You won't believe it, Gus, but that was a road call from the man Silas gave your name to. The car backfired so hard it blew an exhaust joint. He wants us to come and get him."

"Well, go ahead," said Gus.

"He hung up too soon. I don't know where he's stuck. He said he's near the 'roundabout' off Route 9."

"The traffic circle," explained Gus. "He's at the shopping center, Barnstable said."

Stan returned with a Peugeot in tow. From it stepped a young man with a fair mustache and straw-colored hair.

"Gus Wilson?" he asked as Gus rolled a creeper under the car. "Very decent of you to come to a stranger's help so quickly."

"That's what we're here for," said Gus.

"Name's Neville Sands -- exchange student. The car belongs to some American friends. They lent it to me to see a bit of your country."

Stan came out from under the car. "I slipped that joint back. No sweat."

Sands looked questioningly at Gus.

"No difficulty about that exhaust joint. What's your engine trouble?"

"There wasn't any, you know, until yesterday. The owner had a new condenser, distributor cap, rotor, and points put in before I started.  Last night the motor began to miss. When I stopped for petrol, I had the sparking plugs cleaned, but that did no good.

"This morning an agency mechanic suggested the carburetor was at fault. He cleaned it and installed an overhaul kit. The motor seemed to run better at first, but after a bit it got so bad I had to stop at that car park where your friend met me."

Gus winced where it didn't show. "We'll check it for water in the gas, see if the fuel pump's delivering, and go back over the ignition," he said.

"Good show. I bought a new coil from the agency, with the thought that it might be useful. You'll find it in the boot. I'll have a spot of tea meanwhile. Is there a pillar box close by?"

"Turn left when you go out," directed Gus. "At the end of the block."

Stan was busy. He drained a little water from the gas tank, checked fuel-pump delivery and found it good. He opened the distributor.

The points were properly gapped and in good condition. With the ignition on, Stan flicked them open by hand while holding the coil lead near the block. A rather thin spark jumped over.

"Could be a bum coil," Stan said to Gus. "Where'd he say we could find that new one?"

"In the trunk."

"Ah yes, the bloomin' boot. And what's this pillar box he's going to for his dish of tea?" asked Stan.

"A mail box," said Gus with a grin. "I'm surprised you don't understand the Queen's English, Stan."

Stan grunted, found the trunk key and installed the new coil. But manual opening of the points produced no better spark than before; and when he started the engine it still ran very roughly, with occasional back-pops, as if it might be out of time.

"I checked the firing order, and the plug leads aren't mixed up or so close they'd be crossfiring," Stan said as Gus came over to the car.

"If he hadn't said that this condenser is brand-new, I'd yank it and try another."

Gus nodded. Suddenly he switched off the droplight Stan was using. "You've hit it -- almost. Look at that."

He pointed at the condenser, which was mounted on the outside of the distributor case. Small red sparks flickered around the mounting screw. Gus pressed a screwdriver against it.

Instantly the bucketing engine settled to a rhythmic idle.

"Wizard!" said Sands when he heard the smoothly ticking engine a little later. "Compared to you, those other mechanics were rather clods."

"Only the first one's to blame," said Gus. "He must have lost the metric-thread screw and used a slightly undersized American one.

When it loosened, the condenser was ungrounded."

Sands frowned. "Oh, I say, you mean unearthed? Perhaps I'm the clod. Always thought a condenser was merely to keep down static in the wireless. What's it do, really?"

"Other condensers do kill radio interference," said Gus. "But the vital condenser is in the low-tension ignition circuit. When the points close, current flows in the primary winding of the coil and sets up a magnetic field around it. But it's when that field collapses that it induces a high-voltage current in the secondary, which fires the plugs.

"Connected across the points, the condenser acts like a tank or reservoir. When the points open, the primary current rushes into it, letting the magnetic field collapse in milliseconds. That fast drop generates a strong spark. Also, by absorbing the interrupted current, the condenser prevents arcing and lengthens point life."

"And that loose screw cut the condenser out?" asked Sands.

"Yes, intermittently," said Gus. "With no condensor, the primary current tried to jump the points by arcing across them, so the coil's field didn't collapse fast and the spark was weak. Arcing also delayed the break, making the spark so late that it sometimes fired when the rotor had moved to the next cylinder. And that was what caused the backfiring."

"I'm really much obliged," said Sands. "Now, if I may settle my account and be on my way . . ."

"How come you caught on to this guy's lingo," asked Stan as he and Gus were closing shop, "when it threw me?"

"Oh, I read an English car magazine now and then," confessed Gus. "Keeps me up to date on foreign cars."

"You never got 'pillar box' that way. For somebody who lost sleep over a late movie, Gus, you were pretty sharp -- still hitting on all cylinders."

"You know, old top, even that helped!"

"What? The late show?"

"Uh-huh," Gus said with a grin. "It was an English movie."

END