The subway system's Farecard machines are less likely to be out of order now than they were two years ago because of recent improvements in maintenance, according to Metro officials.

But officials say a multimillion-dollar overhaul of the trouble-prone fare collection equipment is needed to reduce what they consider an unacceptably high rate of malfunctions.

Because of the stepped-up maintenance, fewer Farecard machines are reported broken when subway stations open on most mornings. According to recent Metro statistics, about 4 percent of the 372 ticket-dispensing devices are on the blink by 7 a.m. In 1983 and early 1984, the total was about 15 to 20 percent.

Nevertheless, many machines go out of service during rush hour and later in the day because of chronic ailments and long-term wear and tear. One out of every 280 Farecard puchasers encounters a mechanical jam or breakdown, the authority's statistics indicate.

As the apparatus ages, officials said, malfunctions likely will increase. Under existing contracts, the Farecard system already is expected to cost Metro more than $70 million, largely in federal funds. The proposed overhaul has been estimated at an additional $22.7 million.

Metro's efforts to revamp Farecard maintenance began about a year ago. In an initial move, repair crews were assigned to work on weekends. As a result, fewer machines were out of order on Monday mornings.

Since then, officials said, Metro has reorganized its Farecard maintenance staff to accelerate repairs. Steps also have been taken to increase supervision, speed reporting of malfunctions, carry out more preventive maintenance and curtail gaps in spare parts supplies, officials said.

Two years ago, a $5.3 million overhaul of the electronic gates through which passengers walk after inserting their Farecards resulted in a sharp reduction in malfunctions. Officials said they expect a similar improvement after the ticket-dispensing machines are overhauled.