Former medical student Morris Kravecas, who just completed his residency at Georgetown University Hospital, says he wants to pay back the $12,000 in education loans he received from the federal government during the late l970s, but right now he can't.

Kravecas, who says he made only $1,376 a month during his five-year residency, said, "I have so many loans going I cannot keep track of who I owe what. I must owe over $50,000 easily. I certainly can't pay $12,000."

The explanation of why Kravecas has not yet repaid his student loan sounds reasonable enough, as do those of many other student loan defaulters. But the Department of Education is now saying its sympathy has limits.

Kravecas, being sued in U.S. District Court in Alexandria by the department, is among 16,000 loan defaulters being taken to court across the country to force repayment of about $48 million in federally guaranteed student loans -- some dating back to the early 1970s.

The court actions, which have collected about $5 million since they began last December, are part of a stepped-up effort by the department to collect $4.1 billion in defaulted loans, according to Richard Hastings, the department's director of debt collection.

"We've been turning up the heat gradually over the past four years," said Hastings. The latest increase in temperature came this week when Secretary of Education William J. Bennett announced he is asking the Internal Revenue Service and state tax agencies to withhold tax refunds next year for 2 million loan defaulters.

"All we're asking for is to be put in the hat when it comes time to decide who to pay every month," Hastings said.

"People are making economic judgments," he commented. "They look at loans which carry 7 or 8 percent interest and their credit card bills, which carry 21 percent. They pay the one with the larger interest."

Hastings quickly added that 90 percent of those who took out guaranteed student loans have paid them back and the new measures apply only to the 10 percent who are delinquent.

Among the 120 people sued by the U.S. attorney's office in the Eastern District of Virginia are an Alexandria dentist and an employe of the Fairfax County School system.

"There are some people who are working but who are not in a financial position to pay," said Assistant U.S. Attorney Dennis Szybala .

"But I've also seen some real yuppie deadbeats with good-paying jobs, driving around in Mercedes who won't pay or who have stiffed Uncle Sam," he said.

These two extremes, however, are in the minority and about 50 percent of the cases are resolved by payment schedules, Szybala said.

Most of those contacted by a reporter to find out why they had not repaid their student loans had a ready explanation. In many cases they had not been informed of the suits.

"There's a suit against me in Alexandria? Oh my God," said Michael D. Woodard of Springfield, who just received his doctorate in sociology from the University of Chicago in December.

Woodard said he previously has tried to explain to Education Department officials that he is up to date in his loan payments and that the government is trying to make him "pay the same loan twice, which I refuse to do."

James A. Ott, a software technician for Honeywell Inc. in Fairfax County, said a loan for $1,745 he took out in l975 was for a course in television repair.

He couldn't complete the course because he was sent to Korea by the U.S. Army, but the government paid the school anyway, and now wants to collect from him.

"I'm guilty. It's been a skeleton in my closet," was the unusual response of Alan E. Byrd, a technician at Nasi Auto Repair in Vienna. Byrd said that while in the U.S. Navy he started to repay a 1975 loan for $2,464 but "they returned all my checks.

"I kept trying to get hold of somebody to find out how much I owed and to see if I could set up an arrangement, but they wanted a full check. I told them I didn't have $2,400." Since being sued, he has started to work out a payment plan.

Stephen L. Wright of Alexandria, a data base clerk with Bell Atlantic, said he just does not have the money to pay the bill. Wright said he took out a student loan of $2,850 in 1972 while he was working in a steel mill in Wheeling, W.Va. Since then he has had two long periods of unemployment but didn't ask for a deferment.

Last December he talked to department officials and "I showed my desire to pay at that time. It was just a matter of economics, I just did not have the money. We're just now getting on our feet, but here they are taking us to court."

Kravecas said he and his brother, who is a lawyer, wrote letters to all the institutions to whom Kravecas was indebted in order to set up repayment schedules. "They were all very reasonable; they asked how much can you pay?" he said -- except for the Department of Education.

"They wanted me to pay $1,000 a month," when his monthly paycheck only came to $1,376, he said. Kravecas says he will gladly pay off the loan when he starts his own ear, nose and throat practice in Miami in November.

"I really feel a responsibility to pay it back because I appreciate their lending it to me and because maybe it's going to help someone else get through medical school. Or they can build another bomb with it; it's their money."