Soviet transition may have already begun. Younger men have quietly been moving into the leadership

The Soviet capital, a month after Soviet leader Konstantin Chernenko dropped from sight, does not seem to be a city primed for the turmoil that would arise from a transition in leadership. The reason could be that the transition has already begun -- and may not be as profound as many in the West expect.

That, at least, is what some analysts here in Moscow are saying as rumors proliferate about Mr. Chernenko's health.

``High people have said that he's ill. They've said it as if they mean it, and as if it's serious,'' says a senior Western diplomatic source.

Other sources here have suggested Chernenko may be about to resign -- an unprecedented step for the Soviet Union.

Inevitably, the discussions go beyond Chernenko to possible successors. The man most frequently mentioned is 53-year-old Mikhail Gorbachev, the youngest man on the ruling Communist Party Politburo, who completed a successful trip to Britain and Scotland last month.

Should Gorbachev accede to the leadership, this would undoubtedly be heralded as the inevitable generational change that was sure to take place as the Kremlin's aging leadership passed from the scene.

But one Western analyst, echoing other Kremlin-watchers, says that the generational change has been an ongoing process.

It has, he says, been taking place since the last years of former Soviet leader Leonid Brezhnev. (Mr. Brezhnev, after all, brought Mr. Gorbachev into the Politburo.)

The generational change continued through the brief tenure of Yuri Andropov, as literally hundreds of regional and city Communist Party officials were replaced, along with many key figures in this country's industrial enterprises.

``The thing that I'm struck by,'' one diplomat remarked last fall, ``is how much the generation change has already taken place.'' And, he added, this change has apparently made little difference in the Soviet Union's economy or political system. The reason, he says, is that most of the changes have been -- and are likely to continue to be -- ``at the margin.''

Why? For one thing, this country operates under a collective leadership (the Politburo), which currently has 11 full members, with an average age of 67. Throughout the last two transitions, it has ensured a remarkable degree of stability and constancy in executing policy.

The notable exception is in foreign policy, where the Politburo apparently changed course and allowed Foreign Minister Andrei Gromyko to reopen arms control negotiations with the United States. Even so, analysts here are quick to point out that the tactical switch did not amount to actual concessions over matters of substance.

``Substantive innovation . . . wouldn't be any less difficult [under a new leader] than the current leadership finds it now,'' says a Western diplomat, because the country can proceed ``only so far as the Politburo can maintain a consensus.'' That consensus must be maintained, he says, no matter who has the title of general secretary of the Communist Party.

If Chernenko relinquishes his post, it would shatter historical precedents. Although reports of Chernenko's state of health are still fragmentary, and often conflicting, there are persistent rumors that Chernenko will indeed relinquish the office. At least two British newspapers have carried reports to this effect, attributing them to Soviet sources.

Those Soviet officials who do pass along such reports claim not to have first-hand knowledge of Chernenko's health. But the mere fact that they are willing to give negative reports is a departure from past practice. When Mr. Andropov's health declined precipitously, for example, some of these officials dutifully clung to the official story that he had a cold.

``There's more talking this time,'' says a high Western diplomat.

Some well-placed Western analysts also suggest that resignation is a serious possibility. Others do not rule out the prospect, but don't consider it likely. And still others flatly discount the notion.

The rumors are not limited to diplomats. They are also circulating among the populace, but don't seem to be given much credence.

Two coming events could give further insights into Chernenko's health. On Feb. 11, Greek Prime Minister Andreas Papandreou is expected here on an official visit. Normally, he would be expected to meet with Chernenko, although protocol requirements would be satisfied if he met with Prime Minister Nikolai Tikhonov.

And elections to the Supreme Soviet, the country's nominal parliament, will be held on Feb. 24. Chernenko is standing as a candidate in those elections. (He is unopposed.) Normally, he would deliver a campaign speech in the last few days before the election. However, someone could read the speech in his stead.

Meanwhile, the Kremlin proceeds on what might best be described as ``automatic pilot.'' Decisions are being made, diplomats say, though perhaps with less certainty and dispatch than would be the case with a healthy leader.

In particular, Mr. Gromyko seems to have a fairly free hand in negotiations with the US. The Soviets have presented new proposals at the Conference on European Security in Stockholm. And they have managed to bring the US into discussions over the situation in the Middle East -- a longtime Soviet goal.

Domestically, however, there are few signs of movement, though analysts will be watching quite carefully the outcome of a meeting of the Communist Party Central Committee later this year. It must, in theory at least, approve any major changes in the party leadership -- including a new party general secretary.