It is 1.40pm on a Wednesday but one unit on the fourth floor of Ang Mo Kio Hub is buzzing. Around 60 people mill about or sit in front of machines as electronic jingles fill the room.

There is free instant coffee and tea, and free Wi-Fi. The password: 1818181818. In Mandarin, it sounds like the phrase " easy to prosper", repeated several times.

Welcome to the Scarlet City jackpot room run by NTUC Club, with 40 fruit machines and a mostly retiree clientele. Such rooms were thrown into the spotlight after a check by The Straits Times during the run-up to yesterday's Football Association of Singapore elections found that Tiong Bahru Football Club had a revenue of $36.8 million in one year, with most of it coming from the jackpot machines.

Scarlet City sits in a corner of AMK Hub, next to the cinema and arcade, by the escalators and lifts. There is no loud signboard, only a discreet pair of opaque doors labelled "in" and "out", which open every few minutes as NTUC members enter or exit, giving passers-by a glimpse of punters sitting before flashing, lurid lights.

One retiree, who wanted to be known as Mr Tan, told The Sunday Times: "I've nothing better to do, so I while my time away here." The former cabby, 74, has been visiting Scarlet City almost every day for a decade. Some days, like on Wednesday, he would blow $50. Others, like on Friday, $200 or $300.

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Mr Tan had long exhausted his $50,000 savings. He spent his CPF on housing, and now makes do with the $500 he gets from his children each month. Does his heart ache? "I'm used to it, I'm numb," he said.

Money disappears quickly in jackpot rooms.Each pull of the jackpot at this club can cost anywhere from 80 cents to $30. For those who run out of cash, the handy cashier will let you buy credits using your ATM card.

At one machine, this reporter's $10 whittled to $3 in a few minutes. Then, jackpot - as it announced some free games and a 920 credit win, which translated to $18.40 and an overall $11.40 gain.

By then, two retirees had gathered around. "Stop playing and cash out," they urged. The odds are against the punter, they said, so it is best to leave once you make a winning and not be greedy. They claimed to be there only for the free coffee, not the fruit machines which they said had led to the downfall of a few regulars.

"There was a guy wearing a cap, he lost more than $50,000 in three days! Young people like you, it is best not to get addicted to gambling," one of them said.

Such advice and horror stories were a common refrain from the old folk in the room.

Madam Wong, 70, a part-time housekeeper who lives in Serangoon, said one woman told her she had lost her flat to jackpot gambling. But Madam Wong said she has discipline and gambles only "a few times" a month.

"I'll bring only $50 and not my ATM card. By 3pm, I'll leave to buy my groceries at NTUC downstairs," she said, referring to the NTUC FairPrice Xtra supermarket downstairs.

But their sound advice ran counter to the punting in the room. While there were around 60 people on Wednesday afternoon, Friday saw almost 100 and full occupancy of the 40 machines.

Most punters were retirees, with a handful in their 40s and one 21-year-old polytechic student.

In comparison, the jackpot room run by Gombak United Football Club had only one gambler in his 40s when The Sunday Times visited at 4pm on Wednesday.

Such jackpot rooms are way too accessible, said social workers, and the barriers to entrance are low.

Mr Billy Lee, executive director of Blessed Grace Social Services, said the casinos' $100 levy acts as a deterrent, whereas some jackpot clubs offer free membership and others charge just $5 or $10.

Out of the 500 gambling addicts who go to Blessed Grace Social Services for help each year, about 10 per cent are addicted to fruit machines. And most, he said, went to rooms operated by NTUC Club or Safra. Together, the two operate 11 such clubs in heartland areas such as Jurong, Punggol, Tampines, Ang Mo Kio and Choa Chu Kang.

In the financial year that ended March 2014, Safra's fruit machine takings totalled $24 million. In contrast, its gyms barely brought in $3 million in the same year.

NTUC Club declined to comment, but it has been reported it would not be financially viable without the millions from jackpot machines, which help to pay for the rides and other facilities.

In all, Singapore has 84 private lottery clubs as of 2015. In that year, duties collected from fruit machines totalled $213 million.

Mr Lee said the accessibility of these rooms had led to a higher recidivism rate.

He has a success rate of 50 to 60 per cent with reforming gamblers addicted to horse racing, casinos or online betting, but that figure falls to a measly 10 per cent for jackpot addicts.

"It's definitely a problem," he said, adding that these rooms should also charge a $100 levy or be moved to more remote areas.

Dr Thomas Lee, a psychiatrist who works with gambling addicts, said the Government should ensure the jackpot rooms have posters and brochures about problem gambling, and display the National Council on Problem Gambling helpline prominently.

"They should also train jackpot room staff to identify and advise clients who may exhibit problem gambling behaviour," he said.