SOUTH PORTLAND — A sign posted in the window of Uncle Andy’s Diner reads: “Customers Wanted. Apply Within.”

Be careful what you wish for.

In the weeks following an early June visit from Robert Irvine, chef/host of “Restaurant Impossible” on the Food Network, the diner at 171 Ocean St. was so popular that a line stretched every day from the front door down to the next block, according to Andrea Fogg, a waitress and daughter of the owners, Dennis and Tina Fogg.

“It helped us out a lot,” she said of the TV show that swoops in to transform struggling restaurants. “We were close to closing when they came and helped us.”

The crowds have since dissipated, which Fogg attributes to the busy back-to-school season. On Tuesday, around noon, the place was practically empty except for Philip Marshall, a retired Realtor from Gorham, and his friend Mel Corey, a retired businessman from South Portland – a couple of regulars enjoying a cup of coffee after a late breakfast of French toast, sausage and a side of home fries.

“We come in in the mornings sometimes and it’s packed,” Marshall said. “We still enjoy coming in, and we like the owners. They’re very nice people.”

The Uncle Andy’s episode, called “No Laughing Matter,” will air for the first time at 10 p.m. Wednesday on the Food Network. Subsequent air dates are Thursday at 1 a.m., Sept. 3 at 11 p.m., Sept. 4 at 2 a.m., and Sept. 6 at 2 p.m.

Irvine’s team gave the diner new tables and chairs, a fresh coat of apple green paint, flat-screen televisions, a new alarm system, different light fixtures, and enlarged, framed photos showcasing scenes from the 60-year-old diner’s past. The restaurant kept its horseshoe-shaped counters, with updated stools. The menu had its own makeover as Irvine added dishes such as a lobster omelette and grilled Dijon chicken.

Andrea’s father, Dennis Fogg, still makes his signature pancakes in whimsical shapes for children, but he has stopped telling customers jokes and doing his mini magic routine (think pulling coins out of children’s ears) so he can concentrate on helping the staff handle all the new customers. That makes Andrea Fogg a little sad, “but we can’t complain,” she said. “Business is good.”

The big reveal occurred on June 11. In the days following, there were so many customers at the diner that some of the staff couldn’t handle the crush and left. Customers who were lucky enough to get into Uncle Andy’s complained online about the poor service.

“I understand where they’re coming from, but they also need to understand how we’re dealing with this,” Andrea Fogg said. “We’ve never had this many people before. It was a big change to go from nothing to, like, really popular in four days.”

Fogg said they eventually hired three new people to help handle the increased business.

Some customers who saw the long lines gave up and said they would come back later to catch a glimpse of Uncle Andy’s facelift.

“We’re just getting those customers now, the ones that wanted to wait awhile,” she said. “We get people all day, every day, saying they’ve never seen (the renovations) before.”

Marshall and Corey said they come in a little less often than they used to, but they like the renovations at the diner.

“We couldn’t believe it when we saw the change,” Marshall said. “I think the menu’s been better.”

“The food’s always been good,” Corey added.

“It’s more of a variety now,” Marshall said.

Marshall said Uncle Andy’s isn’t “as laid back as it used to be,” but that’s OK with him because the Foggs are “doing a lot more business.”

Fogg said she misses the more casual atmosphere sometimes – the days when she could sit and talk with regular customers and hear about their lives, though she is beginning to have more time for that now as the crowd tapers.

“We weren’t surviving off just regular customers,” she said. “We needed brand new faces. And now that it’s modernized and up to date, people actually want to come in and sit.”