The Gilbert and Sullivan Players have mounted a thoroughly banal version of Ruddigore at the Agassiz. That the show is nonetheless delightful is one proof more that nothing but a tone-deaf cast and orchestra can wreck these comic operettas.

In the current production, Gilbert's burlesque of late 19th-century melodrama is presented all but dead-pan by actors nearly as immobile as the lectern-bound participants in a dramatic reading. Having abandoned all but the most incidental attempts to give character to his leads or to fortify the humor of the text with sight gags, Paul G. Cooper reduces himself from a director to a variety of quartermaster. His sole purpose and accomplishment is to deliver the proper number of actors to any part of the stage which will accommodate them, in time for the musical numbers. No 18th-century or war could have been as staid.

Cooper's abdication is all the more disastrous because rapid changes of character are the essence of the play; for they parody the mechanics of melodrama while they suggest often-embarrassing affinities between a figure's old pose and his new one. Of the male leads only Stuart Rubinow displays the emotional range necessary to do justice to the hectic script. His Sir Despard Murgatroyd is first exuberantly wicked as the bad baronet who pays for his sins by contributing to the Church. Several abrupt turns of the plot later and on the right side of the law, he is a flawlessly pompous rate-payer who has spared himself the need to repent his sins simply by disowning them.

Among the ladies, only Chalyce Brown can match his performance. As Mad Margaret, an envious witch and later wife to Sir Despard, she charges happily from wild laughter, to perfectly-controlled song to dreamy, moon-struck soliloquy. Sad to report, her part is smaller than her gifts.

THE OTHER ACTORS are more or less monotonic. Martin L. Kessler does nothing with the part of Robin Oakapple, the would-be do-gooder in that lingering line of n'er-do-wells, the Baronets of Ruddigore. Where he should be ridiculously eager, he is listless; where he should be bottomlessly downcast, he is listless. On the other hand, John B. McKean, who plays Oakapple's foster brother, is ceaselessly, aimlessly and rather awkwardly energetic. He is always swirling, prancing and dance-stepping. His good intentions and obvious relish for the part can neither overcome nor excuse the peculiar dialect in which his lines are delivered. There is no saying for sure, but, perhaps, a boy from a good neighborhood somewhere in the South trying to imitate a boy from a bad neighborhood in Liverpool could sound as he does. His voice, like Kessler's, is adequate for the demanding part.

In the same way, Susan Larson is something of a disappointment as Rose Maybud, a characteristically Gilbertain example of innocent rural lust. Her singing voice is pleasant enough, but she walks through her lines, apparently baffled by the splendid prop she carries, a book of etiquette. Of all the cast she might have benefited most from stage direction.

The orchestra performed carelessly Saturday night; and several songs ended with a few unscored notes from the woodwinds and strings. But James Paul's direction is as powerful as ever, and by mid-week, things will surely be tidied up.

This carping aside Ruddigore must be counted in good measure a success. The songs are skillfully performed and the libretto is still recognizably one of Gilbert's funniest. Randall L. Darwell's set is, as usual, a pleasing contraption. Still, I urge you to leave the few remaining tickets at the box office. One or two empty seats at the back of the Agassiz might convince the Gilbert and Sullivan players to stop paying exclusive attention to the things they do well and consider some they don't.