FOR THE Kennedy Center and its chairman Roger L. Stevens, 1979 has been jam-packed with adversities: An internal squabble that lead to a major personnel shuffle, an unresolved congressional debate over the Center's long-term debt, intensified criticism of its booking policies from producers and politicians, major physical repairs, labor problems, several serious box-office disappointments (compounded by the gas shortage) and, for Stevens himself, a heart attack, his second.

With all these troubles, it was easy to regard the Kennedy Center as an institution that had lost command and fallen dangerously behind the times. But obscured by the calamities, the Center has taken steps this year to broaden its role -- steps that, however, inconspicuous, could prove to be more important than the problems.

In the theatrical realm, Stevens and Joseph Papp -- an unlikely-sounding combination -- began serious discussions about creating a joint repertory company with major box-office stars, to perform here and in New York. The concept of a "national repertory company" has often been talked about, but never by two producers of such influence (or such apparently divergent tastes).

Another promising partnership, definitely sealed; will bring the Metropolitan Opera Company to the Kennedy Center in April.In the past, the Met has sent touring productions into the acoustically diffuse surroundings of Wolf Trap, but Washington will now see productions more like those mounted at the Met's New York home, and in a smaller auditorium widely praised for its acoustics.

In theater, opera and dance, the new Terrace Theater has given the center the flexibility to present more esoteric and adventurous works. A play-reading series in the under-utilized Musical Theatre Lab has opened yet another door to new authors, actors, and audiences. In general, Stevens, and his associates seem to have made a determined effort to show that the Center, sometimes identified with the big and bland, can do the small and slightly outrageous, too.

The vision is alluring: an arts complex offering commercial, middle-of-the-road entertainment alongside subsidized avant-grade shows and works-in-progress, appealing to people in blue jeans and black tie all at once. Will it work? No one can say, but many who know Roger Stevens are inclined to give him the benefit of the doubt.

Both supporters and critics agree that the Kennedy Center, to an astonishing extent for an institution so outwardly vast and impersonal, is a product of this one man's enormous zeal and shrewd judgment.

When John F. Kennedy was assassinated in 1963, Stevens, who had spent two hard years on the plans for a national culture center, moved with almost unseemly swiftness to have it designated a "living memorial" and the "sole" national monument. The Kennedy family seemed more interested in building a library in Massachusetts, but the White House and Congress were persuaded to give top-priority status, and $15.5 million in matching funds along with $15.4 million in loans, to a performing arts center on the Potomac.

Named Lyndon Johnson's special consultant on the arts in 1964, Stevens showed the depth of his commitment by moving permanently to Washington and, for the next five years, laregly abandoning his career as a producer. He also vigorously resisted a last-minute compaign to have the project split and moved downtown. And as projected construction costs kept rising (from an original figure of $44 million to an eventual $74 million) he patiently scraped together a package of addition support -- including $7.5 million more in direct federal money, $5 million more in loans and a $3.5-million advance from a contractor against projected parking revenues. At the same time, Stevens not only met but surpassed the goal of $23 million in private contributions (including gifts from foreigh governments). The Center calculates it has received some

All this while, from Stevens' perspective, the Broadway establishment showed little interest or faith in his project. "I didn't see any New York producers trying to help us raise money," he says. So it angers him that several New York producers are now complaining about a lack of access to the center, and acting as though its success was a foregone conclusion, not something that stemmed from the strenuous efforts of a small group of enthusiasts under Stevens' leadership.

(The criticism has been lead by producer Emanuel Azenberg, a widely respected producer and road manager who has presented every Neil Simon play since "The Sunshine Boys," plus the Broadway hit "Whose Life Is It Anyway?" He also managed touring companies of "Ain't Misbehavin'" and "The Best Little Whorehouse in Texas." This fall, he produced Frank Gilroy's "Last Licks" and Abe Polsky's "Devour the Snow" -- both serious, uncommercial-sounding plays that closed immediately.)

Stevens' critics have accused him of favoring "elitist" English playwrights over the domestic likes of Neil Simon and Sam Shepard (who have never had plays performed at the Kennedy Center), and they have questioned the Center's receptivity to shows with black or minority themes. The Center has responded with figures and titles to combat both charges, but Stevens is the first to fault some of his most recent choices.

A revival of Somerset Maugham's "Home and Beauty" last spring was only one of the several projects that failed to catch fire with audiences this year. "Home and Beauty" did not even complete is scheduled engagement. Nor did "More from Story Theater." And "Camelina," an ambitious musical with a score by Alan Jay Lerner and Burton Lane, lost about $1 million when Stevens and his partners brought it to Broadway

To make matters worse, the Center's Theater Guild subscription rolls have declines by about 2,000. "That's what happens when you do a bunch of dogs," Stevens explains, with his usual directness. Azenberg has described an engagement at the Kennedy Center, on subscription, as "four weeks out of town with no risk," but Stevens says "I can name five other cities where the subscription is much better than ours."

The Center's board of trustees has been in a critical mood, too. An ambitious spring festival devoted to "Paris: The Romantic Epoch" lost some $90,000 beyond the anticipated $190,000 deficit, and audiences were unexpectedly sparse for the Cuban National Ballet. And the first season of the Summer Opera series lost $437,000 -- $150,000 which was covered by private donations. In September, outraged trustees rebelled against what they saw as a devious effort by Martin Feinstein, the former executive director for performing arts, to launch a full-scale Kennedy Center opera company by furtive degrees.

Warned by former senator J. Wililiam Fulbright that Congress would not like to see the Center undertaking new commitments before it had resolved how to pay the $17-million interest on its construction debt, the trustees demanded that Feinstein's authority be cut back. (He now serves as the Center's director of opera and ballet, in addition to his new post as director of the Washington Opera.)

"We were not about to appear to take on the (financial) burdens of the Washington Opera," explained Sen. Charles Percy (R-Ill.), vice chairman of the board.

In October, as if these were not problems enough for one year, Stevens suffered his heart attack. As he lay recuperating in a San Francisco hospital, it seemed all too logical to suppose that the time had come for a changing of the Kennedy Center guard. But a few weeks later, Stevens, 69, was back at work with neither his authority nor his energy significantly diminshed. And as he planned for the future, prestigious voices sprang to the defense of what he had done in the past.

"I'm glad he's the head of the Kennedy Center," said producer Arthur Cantor. "The sea is full of sharks. He's not one of them. I see nothing wrong with 'elitist' taste. I think we could use a lot more of it. He does have an aversion to f -- and s -- plays, but who can blame him?"

"Roger is being pilloried right now for not producing four playwrights," said still another New York producer, who asked not to be identified. "It seems to me that David Mamet, David Rabe and Sam Shepard are being yoked very unnaturally to Neil Simon. [All four have been cited as worthy American playwrights by the Center's critics.] In the aggregate, they have had maybe three Broadway productions. On the whole, these are people who write plays for the 199- and 299-seat theaters. The Kennedy Center would be bankrupt if they had those playwrights.

"The truth is that Manny Azenberg, so far as I know, has not chosen to produce Rabe, Shepard or Mamet on Broadway. And the Kennedy Center has, after all, put on an Arthur Kopit play ['Wings'] in the last year, and it put on 'On Golden Pond.' As for Neil Simon, he is not lacking for productions."

Sen. Percy may have seized on the best defense of all. "You need a very strong person behind an enterprise of this kind," said Percy. "I like strong leadership. The country needs it. I think we'd by subject to more criticism with weak leadership, with vacillation."

Azenberg says his appeal to the Senate was a last resort, and that "part of me" regrets the whole anti-Kennedy Center campaign -- because of the time and energy involved and the inevitable residue of unpleasantness. "There's been enough blood spilled," he says.

The Stevens-Azenberg split has certainly influenced the shape of theater in Washington. Azenberg's desire to find an outlet here beyond the Stevens orbit led him to help local entrepreneur Sam L'Hommediu refurbish and reopen the Warner Theater for legitimate plays. So far, the Warner's attractions have included Azenberg's "Chapter Two" and "Ain't Misbehavin'," with "The Best Little Whorehouse . . . " coming next spring. Partly because of the Warner's re-emergence, the National Theatre's board of directors has severed a five-year-link to the Kennedy Center and expects to put the theater under the management of the Shubert Organization as soon as details of a contract can be worked out. It would surprise no one if such Azenberg shows as "They're Playing Our Song" turn up on the National agenda next year.

Directly or indirectly, Azenberg thinks the criticisms have had a "mitigating" effect on the Kennedy Center, encouraging a new emphasis on American playwrights, younger directors and productions imported from regional theaters. Kennedy Center officials acknowledge the shift, but point to different causes -- the opening of the Terrace Theater, principally, and an accelerating effort to do "all the things mandated by Congress but not funded," as Thomas R. Kendrick, the center's director of operations puts it. f

With a generally balanced budget (in fiscal 1979, income totalled $20.25 million -- beyond which the center spent some $43,000), the Center is a "mixed animal," says Kendrick. It is expected to pay for its productions without direct government subsidy, but to look beyond the box office in planning its schedule. (It's policy of fixed, four-to-six week engagements -- a further complication -- makes maximum exploitation of a hit show impossible and works against unusually elaborate productions, which need more time to repay their costs.) This dilemma is probably the strongest answer to the suggestion that a facility built and maintained with federal help should be more freely available to outside groups. If an occasional hit like "Annie" goes to Broadway with the Kennedy Center as co-producer and returns a hefty profit, helping the Center finance less commercial ventures, no one in Congress is very likely to object. (Center officials point out that when it does take on a producing role, it is usually as a minority partner without artistic control, often after an appeal from the original producers for more money. They also cite the vast number of outside producers who have brought plays and musicals to the Kennedy Center.)

Stevens, who has never drawn a salary as Center chairman, expresses concern about possible conflicts of interest, real or apparent. But this worry takes second place to the mission of keeping the Center's theaters filled. A new Tennessee Williams play, "Clothes for a Summer Hotel," was scratched from the spring schedule when the Center's board named Williams to receive one of five annual Kennedy Center Honors. Although neither Stevens nor the Center is involved in the play's productions, "I thought it would look like we were trying to build him up," Stevens explains. Even so, when another spring booking fell through, the Williams play was reinserted.

Stevens has continued to produce or co-produce plays on his own, without Kennedy Center backing. (One of them, Harold Pinter's "Betrayal," is scheduled to open on Broadway next month and, so far, has not been booked into the Center.) Altogether, Stevens as an individual has had a hand in producing eight out of 153 shows that have played at the Center, according to board vice chairman Henry Strong. And, says Strong, in the one case when such a show returned any producer's profit during its run here -- Ira Levin's "Deathtrap" -- Stevens donated the money to the Center.

Even those who say they perceive a conflict of interest concede that Stevens does not seem to have increased his considerable wealth, basically achieved in real estate, from the last decade of his producing career.

The opening of the Terrace Theater, the plans for a repertory company in partnership with Papp's New York Shakespeare Festival and the newly declared independence of the National have undercut much of the current chorus of criticism. But the issues Azenberg and his allies have raised are not the only ones facing Stevens, his enterprise and those who will pick up the reigns on his retirement (a prospect he has been discussing with greater and greater frequency lately).

The minority question goes beyond the number of black plays and musicals performed at the Kennedy Center, or the number of dollars committed to developing future productions. In a metropolitan area whose population is more than one-fourth black, the Center's crowds are overwhelmingly white. Many blacks who could afford the Center's prices simply see it as an alien environment, and there are people of other races who have the same perception.

The Kennedy Center has problems of packaging as well as product -- problems that will persist no matter what the institution does to diversify its fare, no matter how seriously it pursues its discount ticket, education and minority programs. The official colors are red, white and gold. Every element of the decor -- the towering hallways, the statuary, the chandeliers, the flags, the red carpets and the jewel-box look of the theaters themselves -- contributes to a bloodless look that is at odds with the brand of theater represented by, say, a Joseph Papp. And the decor speaks for a larger attitude, which Center officials may see as dignified, but others see as ersatz imperial.

When Papp came down for a recent visit, the columns in front of the Kennedy Center had been transformed from gold to an unexpected green, and he joked that it was the first faintly proletarian color he had seen there. A few days later, the columns were back to gold and brighter than ever. The green it turned out, had been primer paint.