Leon Fleisher's moving return to the full keyboard after 17 years will be broadcast tonight at 9 on channels 22 and 26.

The two works he performs on this program with the Baltimore Symphony, Franck's Symphonic Variations and the Chopin D-flat major Nocturne (No. 2., Op. 27), he seems to playing at least as well as ever.

Technically, everything he does with his troubled right hand, which he is now able to use again after an operation and therapy, works beautifully. Fleisher is now at the point where he is his old self, and more.

That "more" refers to some dynamic and tonal nuances in the Franck that go well beyond his 20-year-old recording of the work with Szell. But it is not just a question of shadings. The more rhetorical moments, which require more than just a lovely lyric line, are also impeccable. The extended octaves and the dotted chords in the last part of the Franck are also splendidly articulated. It was this kind of coordination that first began to trouble Fleisher some years ago when his brilliant career began to run into difficulties because of his right hand.

Originally he had planned to perform the more rigorous Beethoven Fourth Concerto for this opening concert at the Joseph Meyerhoff Hall in Baltimore Sept. 15, but he changed his mind. And he was wise. There is no reason a pianist of his exalted reputation should take on anything like that until he is sure he has it in hand. And beyond that, he has the even more taxing Brahms concertos and the Beethoven "Emperor" to deal with. There is no reason to rush.

In an interview with Tony Randall during intermission he describes some of the angony of his ordeal. "It was desperate," he said, "for about four years I was unliveable with . . . among other things it ruined my second marriage."

Randall calls Fleisher "one of the two or three most exciting pianists of the century." Randall exaggerates. Fleisher is, simply, one of the dozen or so most exciting. What more could one hope to be?