Between rehearsals here on Tuesday afternoon, violinist Eugene Fodor stumbled during a racquetball game and threw into jeopardy last night's Kennedy Center concert by the Fairfax Symphony Orchestra. On the occasion of its 25th anniversary, the soloist had sprained the middle finger of his left hand.

The orchestra normally gets to the Kennedy Center but once a year, and by yesterday morning it was clear that Fodor, a silver medal winner in Moscow's Tchaikovsky competition, was getting no better. So three of the six works on the program were scrapped -- relatively short solo showpieces by Chausson, Wieniawski and Paganini.

And conductor William Hudson was faced with two highly imperfect options: either to play only what was left, or to bring in another soloist without rehearsal. Then he reached violinist David Nadien in New York, who had played with the orchestra earlier in the season, and persuaded him to take the plunge. So those earlier performances constituted at least a token substitute for rehearsing, but the work was the Brahms concerto, which is very tricky any time.

The result was, as they say, better than could be expected. Certainly the music was better, trading Fodor's light trivia (except for the Chausson "Poe me") for Brahms, which is arguably the finest work ever written for violin and orchestra. As for the performance, Hudson stuck to steady, easy paces, and he and Nadien tried to give each other berths as wide as possible. The result, allowing for some inevitable messy detail, was a rather generalized interpretation, sacrificing some of the tricky cross-rhythms that give it such boundless vitality and losing some of the pointed accents in the long lyric phrases that help tie it together harmonically.

Still, for a nonprofessional orchestra it was a commendable achievement under duress. And one thing was especially striking, the beautiful, shimmering sound that Nadien got from the high notes of the violin, well remembered from those days in the 1960s when he was the New York Philharmonic's concertmaster.

In the other, carefully rehearsed, compositions the Fairfax orchestra showed good ensemble, pitch and tone. This is no amateur group of players struggling just to keep up. Even so it was short on the subtleties of dynamics, timbre or phrasing that give fine works their individual sounds. The wit in Rossini's "La Scala di Seta" overture was missing, and only occasionally did its Beethoven Fifth begin to suggest that work's convulsive force.

Finally, there was Joan Fontaine narrating Copland's "A Lincoln Portrait." It was quite respectable, but for Lincoln's words you really need a trace of a midwestern accent, with Henry Fonda, for instance, or, best of all, that matchless recording with the Philadelphia Orchestra and Adlai Stevenson. That's real eloquence.