If ever a talent needed a persuasive editor, it's Don Robertson's. Last season's Miss Margaret Ridpath . . . (p. 449) went on too long and astray too often, but its near-mythic evocation of Midwestern lives dazzled. This season's Make a Wish shows the same gifts of dialogue and detail, but they're sadly disjointed, belabored, and undermined. First, six stories present, in mosaic, the life of narrator Phil Moore, the Eric Sevareid of Ohio TV, bachelor and beer lover. This is an alluring concept, with the same facts popping up in different contexts, and four of the pieces click into place: two Chekhovian fragments involving Phil's brother, sister-in-law (""the only woman I know a man could cut his fingers on""), and niece; a sorry, chance meeting with an old, now-dentured flame; a foolish, on-and-off platonic affair with one of Robertson's large yet comely females. But the others are mood-killing embarrassments: Phil's recollection of a fledgling hotel shack-up, complete with Message (sex can be tender) and Love American Style slapstick; and, equally contrived, the car-accident death of Phil's parents on the night of their 30th anniversary party. Then. . . enter mad Grace McElroy, Ohio housewife, whose murder of her four children (and beheading of the family schnauzer) is presented as an arty play--stage directions, audience participation, sort of Our Town gone grand guignol, and nearly unreadable. And, finally, Grace and Phil are hooked up for a novella in still another style--repetitious but vivid monologues by a dozen new characters--as TV-man Phil covers the murders, Grace's asylum escape, and her (luridly described) dismemberment by an angry mob (hence the grisly title). She ""had sliced up her children like London broil"" because, she said, ""we are all guilty,"" and Robertson has obviously become obsessed with the nature of American violence (vide the Margaret Ridpath finale). But self-indulgence prevents anything remotely profound from surfacing, and the most truly disturbing violence here is in fact Robertson's sabotage of his own talent.