Marine Pvt. Lindsey Scott, who was sentenced to 30 years' hard labor in 1983 after being convicted of kidnaping, raping, sodomizing and attempting to murder a woman on the Quantico Marine Base, took the stand again yesterday, claiming that his lawyer was ineffective and pleading for a new trial.

Scott's case attracted national attention 16 months ago when civil rights groups criticized the military's handling of the investigation and court-martial. The groups charged that Scott, 29, a black military police investigator who had an exemplary service record, may have been singled out prematurely as a suspect by investigators under pressure from senior base officers to make a quick arrest in the April 20, 1983, assault on a white woman.

In a day-long session in a stuffy military courtroom on the Marine base, Scott said yesterday that his attorney during the court-martial, Ervan E. Kuhnke Jr. of Dumfries, failed to prepare or subpoena any defense witnesses before the trial and repeatedly assured Scott that the government's case was weak.

"Mr. Kuhnke told me not to worry about it," said Scott in a strained, but quiet voice. He said "that there was no rush, that he didn't believe the case would go to trial, the prosecutors didn't have a case . . . ,that there was no way I could be convicted."

At one point, Scott termed Kuhnke's attitude toward his defense "lackadaisical."

Under questioning by presiding Marine Lt. Col. Hugh S. Atkins, who was also the judge at Scott's court-martial, Kuhnke acknowledged, "I was convinced that the government didn't have a case."

Asked by Atkins if he had conducted face-to-face interviews with defense witnesses to prepare them for trial, Kuhnke said he had spoken in person only with the victim, plus a military investigator and the Marine Corps magistrate who dismissed preliminary charges against Scott for lack of evidence.

Scott and his former attorney clashed sharply on the number of visits Scott had made to Kuhnke's Dumfries office. Scott said he had been there just once to talk about his defense, while Kuhnke estimated there were as many as 40 such visits.

Scott also testified that he asked Kuhnke to subpoena a number of forensic experts on his behalf, but that the attorney failed to do so.

The hearing, held to supply a record that will form the basis for a decision by a higher tribunal, is expected to continue today and possibly Thursday. After that, it will be up to the Navy-Marine Corps Court of Military Review to let stand the original guilty verdict, order a new trial or dismiss the charges against Scott. A ruling is not expected for several months, Atkins said.

Much of the government's evidence against Scott in the October 1983 trial was circumstantial. The crime scene was never found. The woman at first failed to positively identify Scott in a line-up, and forensic tests to compare Scott's hair and body fluids to those found on the victim's body proved negative or inconclusive.

Prosecutors at the court-martial said the woman was lured from her off-base apartment by a black man who telephoned, identified himself as a member of the military police and told her that her husband had been involved in an accident. The man then picked her up in an automobile at her apartment and drove her to a remote area of the heavily wooded base where he raped, choked, and slashed her with a knife, and then left her for dead, prosecutors said