For the first time since bargaining began last February, negotiators for the National Football League and the striking NFL Players Association were reported today to have made progress on several noneconomic issues as they met in secret marathon sessions with a mediator for the second consecutive day.

But the major issue dividing the parties, the question of how to divide up the $1.6 billion the NFL says it's willing to offer the players, remained unresolved. Mediator Sam Kagel was reported to be planning to address that issue in the early hours Friday morning.

Union sources were optimistic that the 24-day-old strike could be settled as early as this weekend. But management has maintained all along that the union's demand for a wage scale represents a major stumbling block and could cause negotiations to collapse at any time.

The union is seeking establishment of a trust fund to pay the players on a seniority-based scale with performance incentive bonuses, and it says it wants $1.6 billion committed to the fund over a four-year period.

Management says it's willing to spend the money over five years, but it wants to spend the major portion of it on the basis of individual player negotiations.

After a 14-hour session of negotiations and caucuses Wednesday, bargainers talked until 3 a.m. today, then resumed discussions shortly after 9 a.m. and planned to continue round-the-clock if necessary.

Among the issues on which settlement was reported to have been reached were the touchy matters of player medical rights and access to medical records and the question of mandatory urinalyses for drugs. Details on the issues reportedly agreed upon were not available. The question of how to handle player grievances, another major issue with the union, was being discussed this evening.

Kagel, a 73-year-old San Francisco lawyer and a veteran mediator and arbitrator of West Coast labor disputes, was described as being firmly in charge of the negotiations. His style since the mediation process began has been to meet with small groups from each side in an effort to resolve peripheral issues before moving to tackle the impasse over the economic package.

"He's seen it all before," was the way one source described Kagel in the mediation sessions.

Although Kagel has imposed a news blackout on the participants in the dispute, he has agreed to brief the media once daily on how the talks are progressing.

Today he said only that in-depth review and discussion of the proposals and counterproposals from both sides are continuing. "At this time, contrary to rumors and reports, a settlement is not imminent," he said.

That statement came in response to a report from Cable News Network out of Minneapolis that the Minnesota Vikings were preparing to call their players back to practice facilities because a resolution of the dispute was at hand.

Nevertheless, the mediation sessions that began in earnest here Wednesday, after Kagel had been fully briefed by representatives of both sides, represent the first give-and-take bargaining since the talks began. Before Kagel arrived here to begin the process late Tuesday night the two sides had been able to agree only on one subtitle of a noneconomic issue.

Moreover, the sessions here seemed to be free of much of the rancor and acrimony that have characterized previous meetings, which usually ended with each side appearing before the media to denounce the other for lack of progress.

Both sides confirmed that they intend to continue in mediation at the Hunt Valley Inn in this suburb north of Baltimore until the strike is settled. And they agreed that if either side broke off talks it would be risking a public relations disaster.

Kagel, a man of standing and prestige in the field of labor mediation and arbitration, is said to have the power to influence the sides to bend or modify their positions simply by threatening to walk out himself with a declaration that one side or both are not bargaining seriously.

Unlike the mediation efforts in last summer's baseball strike, it appeared unlikely that the parties would meet for a few days, then break off and then meet again, in part because such a procedure would involve transcontinental travel for the San Francisco-based Kagel.

Kagel was chosen to mediate the dispute Monday by Kay McMurray, director of the Federal Mediation and Conciliation Service, after a private meeting with Ed Garvey, executive director of the NFLPA, and Jack Donlan, the executive director of the NFL Management Council, the league's labor negotiating arm.

Both Donlan and Garvey stayed out of sight for most of the day, having meals sent in to their caucus rooms. As is his custom, Donlan did emerge for a predawn six-mile jog. Union officials also said players were being discouraged from eating meals in the dining room to avoid contact with the media.