A month after Yuri Andropov became the leader of the Soviet Communist Party, a new, less visible phase of transition from the Leonid Brezhnev era is under way.
At stake are posts within the Soviet ''policy machine'' - an apparatus that, although lacking the ultimate decisionmaking role of the ruling party Politburo and Secretariat, has grown steadily more intricate and powerful in recent years.
Including policy specialists, party careerists, academics, and interest-group representatives, the ''machine'' works in direct or indirect coordination with Politburo and Secretariat to influence policy decisions.
Mr. Andropov seems generally to be moving with caution, avoiding rapid or wholesale import of new faces - much the pattern of the few changes at the level of Politburo and Secretariat since Mr. Brezhnev's passing.
But the new party leader has overseen his first real shuffle within the policy machine - beginning Dec. 6 with the replacement of a close Brezhnev protege as head of the party youth wing, Komsomol.
And Soviet officials reported Dec. 7 a related shift that would be at least equally important: promotion of an articulate and, in the Soviet context, not overly rigid former newspaper editor as head of the party's propaganda department. He is Boris Stukalin, in recent years chief of the State Committee for Book Publishing, the job being given to departing party youth leader Boris Pastukhov.
Soviet television's nightime news program, although including no formal announcement of Mr. Stukali's appointment, did make a passing reference to him as ''head of the propaganda department,'' in effect confirming the change.
The new Komsomol head, Viktor Mishin,in an inaugural speech, echoed Mr. Andropov's recent calls for greater discipline, innovation, and efficiency in the nation's economy - going much softer, at least for now, on the ''threat'' of Western trappings such as disco and T-shirts to Soviet socialist ideology, a favorite theme of his predecessor.
One element in the reshuffle is unclear so far: the future of the current head of the party propaganda department - which helps define and communicate the leadership's main policies and concerns to the rest of the country.
The shuffle, like Mr. Andropov's own public statements since assuming office, should not be taken as a neat index of the specific policy plans of the new party leader. This remains largely a province for Kremlinological guesswork, a not-too-distant cousin of good science fiction.
But the practical effects of the shift, as filtered through interviews with senior officials on how the ''policy machine'' works, would seem to include:
* Boris Stukalin would seem on his way up. He is probably the main immediate beneficiary of the switch.
* Brezhnev-era Komsomol chief Boris Pastukhov, although not ignominously demoted, has lost substantial input and influence in the everyday decisionmaking process.
* His successor will be working with senior Soviet leaders on any serious economic repair heralded by Mr. Andropov's toughened verbal tone on the issue.
A Komsomol chief often attends Politburo or Secretariat sessions and other specialized policy meetings of party and government officials. This is especially true on issues of the economy - where young Kom-somol brigades are seen as a possible antidote to productivity woes - and of ideology.
Stukalin, the man reported to be getting the party propaganda post, is no Western liberal. A onetime deputy editor of Pravda, he is probably best known abroad for his Moscow book fairs at which various ideologically offensive volumes are nixed. He is firmly committed to the Soviet system and acutely sensitive to criticism of it.
In an interivew with The Christian Science Monitor before the 1981 book fair, he suddenly declared, unprompted: ''Sometimes there is talk about censorship here. I can say this is absolutely false!''
On other issues, he proved to be among the more open and relaxed of some two dozen ranking officials interviewed by the Monitor. In reply to questions, he offered a generally frank explanation of the workings of the Secretariat and Politburo in the Soviet system. And when asked his views on Soviet literature, he had particular praise for a number of the less didactic and more controversial of officially accepted authors.
These included ''village writers,'' such as Valentin Rasputin and Fyodor Abramov, and Kirghiz novelist Chingiz Aitmatov.
As head of what is formally called the propaganda department of the party Central Committee - in fact, a department of the Secretariat - Mr. Stukalin would attend the regular, weekly Secretariat sessions and theoretically would help chart how best to get across Andropov-era policy and concerns to the party rank and file.
Other personnel switches under Mr. Andropov also seem to have been marked by caution.
The new party chief is said by senior officials to have brought along with him a chief of staff, Pavel Laptev, and a foreign affairs adviser, V.V. Sharapov. Mr. Sharapov is a China expert and former Pravda writer.
Yet Mr. Andropov has retained Brezhnev-era foreign policy aide Andrei Alexandrov-Agentov. And at least for the time being, he has retained economic aide Boris Vladimirov, a former associate of longtime party ideological arbiter Mikhail Suslov. After Mr. Suslov's death earlier this year, Mr. Andropov was given his Secretariat post.