NINE DAYS into the Royal Balley's current Kennedy Center engagement (which ends tonight), one looks back at the company's visit with a curious mixture of feelings ranging from admiratin adn gratitude to puzzlement and letdown.

Ever since the troupe's epoch-making first visit to the United States in 1949, the Royal has been regarded here as a paragon of classical balley in the grand style. And with every good reason -- this was the company of Ninette do Valois, Frederick Ashton and Margot Fonteyn, the company that revealed for us the respledent glories of "Sleeping Beauty" and other 19th-century classics, the campnay that taught us the meaning of refinement in stage manners and deportment.

The company still holds a lofty place in our esteem, but changes in the making for more than a decade lead one to wonder for how long. De Valois retired from the Royal's directorship in 1963, and though her presence makes itself felt in a variety of ways, she's no longer an active force in shaping the company's future. Ashton, who succeeded her and held the reins until 1970, continues to be the major source of neoclassic repertory, but at 77, he's naturally not as prolific as he once was. Kenneth MacMillan, who was the Royal's director until 1977 and remains officially the principal choreographer, has given new direction and impetus to the contemporary side of the company repertoire. But under MacMillan and now under Norman Morrice, the present director, the classical style that had been the foundation of the Royal's supremacy has begun to show disturbing signs of erosion.

As an art rooted in a traditional past, classical ballet still needs the kind of curatorial care the Royal has lavished on it, and Americans, in particular, need a model on which to base their own classical efforts. It's well to remember that American Ballet Theatre -- the one company in this country in a position to maintain a large-scale 19th-century repertoire -- didn't have a full-length "Swan Lake" until 1967; the ABT "Sleeping Beauty" is of much more recent village.

It's not just a matter of reproducing old choreography faithfully -- steps and even hrasing lose all significance unless the overall congruent to the time and place of the ballet. American dancers are at a disadvantage in this respect. They are geared up to hop from classics to contemporary works to jazz to modern dance int he flick of an eyelash, as American repertoire requires. This makes ofr unparalleled versatility, but it mitigates trongly against purity of classical style, which is another reason we ahve always looked to the Royal for therapy and instruction.

In many respects, the Royal is still capable of giving us those lessons, as the recent performances here demonstrated. The Royal's dancers can still look at home and baroque fornishings and dress; they know how to walk across a stage, lift a goblet to the lips, curtsey and beckon to their companions in a manner that doesn't shriek aloud that this is 20-century make-believe. Their "character dancing," in those national dances that make up the bulk of the divertissements in the classics, is still miles ahead of its American counterpart in style and clarity. They have retained their impeccable sense of ensemble -- the dancers are as much concerned with their relation to one another as they are with projecting themselves,which is seldom the case in American productions. And, by and large, the Royal dancers remain adept at mime, which is so often slighted or bungled on these hsores. The mime passages in classical ballet aren't trimmings but essentials -- they are to ballet what recitative is to opera, the prose statements that convey the narrative. The Royal dancers understand that mime is in itself a mode of dancing -- movement that must be paced, shaped and inflected in a musical fashion.

But the hard-core dancing in the "Swan Lakes" and "Sleeping Beautys" we've seen from the Royal this time has been surprisingly flawed, rom principals on down through the corps. There were exceptions, to be sure: Anthony Dowell as Siegfried, reportedly (I was unable to catch the performance) and Lesley Collier as Odette-Odile in "Swan Lake;" Collier again (though unconvincing dramatically) as Aurora, and Stephen Jefferies as Florestan in "Beauty." But elsewhere, the technical and even stylistic standard seemed to be slipping. Not one pair of dancers who undertook the "Bluebird" pas de deux could fully cut the mustard, which for the Royal is shocking. In general, throughout the Tchaikovsky ballets, one saw insufficiently stretched torsos and limbs, poorly supported feet, imperfect turnout, floundering balance, plus a deterioration in placement and line often enough to give one pause.

Why this is happening is something of a mystery. Arlene Croce, the respected New Yorker critic, in her recent assessment of the Royal, goes so far as to declare taht "it is no longer a classical company" in orientation, attributing the switch to what she calls the "Tudor strain -- thick, dark, Teutonic, quasi-dramatic" in the recent work of MacMillan. Some observers talk of change in the complexion and strength of the Royal coaching staff. Whatever the reasons -- and there are probably many -- this new turn in the Royal is alarming.

Of course, every company passes through evolutio;nary cycles, and just now, at its 50th birthday, the Royal is clearly in transition. The top ranks here were thinned out considerably -- Fonteyn, Lynn Seymour and Antionette Sibley are out of the picture; Dowell was elusive (even before his accident he had only five performances scheduled for the whole Washington run); Monica Mason was given only two subsidiary assignments. On the lower rungs of the Royal ladder appeared some women of notable promise, among them Pippa Wylde, Genesia Rosato, Bryony Brind, Fiona Chadwick and Karen Paisey, but it's hard from present perspective to say how far they can go and how fast.

The Kennedy Center repertory, too, had its pluses and minuses.The execrabel "Isadora" has been flayed sufficiently elsewhere, but the riddle of how as capable and gifted a choreographer as MacMillan could go so wide of his mark remains troubling. The "Sleeping Beauty" production seems as close to exemplary as one is likely to come in this world of compromise; the "Swan Lake," on the other hand, raises doubts about the wisdom of retaining Ashton's Act IV, beautiful as it is on its own terms -- if the Royal isn't going to preserve the original, nd captivating, Ivanov choreography for us, who will?

The only trouble with the Ashton portion was that it was too small. "Daphnis and Chlow" and "A Month in the Country," even wtih less than ideal casts, were a blessing, but it would have been grand to see as well the three other Ashton ballets the Royal took to New York -- his recent, brilliant "Rhapsody," created for the Royal's 50th anniversary and Baryshnikov; and two earier masterpieces, "Symphonic Variations" and "Scenes de Ballet."

In a way, the most hopeful item was MacMillan's "Gloria," his expressionistic abstraction to the music of Poulenc, inspired by memories of World War I. After giving the work a mixed, lukewarm review on initial viewing, I went back for a second performance and found myself being wholly converted to its novel movement language and darkly impassioned poetry. What's especially notable about MacMillan's idiom here, as distinct from Jiri Kylian's in the latter's similarly conceived "A Soldier's Mass," is the strong classical base from which MacMillan operates. Indeed -- in spite of "Isadora" -- in MacMillan's classical grounding, musical sensitivity and originality may lie some of the brighter hopes for the Royal's creative future.