"Songbook" is a good idea for a musical revue--sort of.

It has some passingly amusing lines, plus a handful of half-clever numbers, and I wouldn't blame the five performers who are trying to make it all into something more at Olney Theatre. They're affable, hard-working people and it's not their fault that "Songbook" is one of those enjoyable shows that really isn't enjoyable enough.

The "Songbook" in question is that of "the late, great Moony Shapiro," a fictional British composer who "took everything the 20th century could throw at him." What its creators, Monty Norman and Julian More, have imagined is the kind of typical black-tie tribute that show folks always seem to be giving for their own. Here are snippets of Moony's life, kernels of his dubious wisdom, a clutch of his songs, and the remembrances of his friends--all presented with the same deeply felt sincerity that marks the acceptance speeches at the Oscars.

Moony's life bounces back and forth between the heights of success and the depths of failure, in keeping with the general view that equates the show-biz biography with the roller coaster ride. Since Moony is a bit of a keyboard chameleon, "Songbook" also apes some 50 years of changing musical fashions, starting with his Gershwinesque "East River Rhapsody" (from "Feldman Follies of 1926," notes the program) and ending up with his hot disco hit of the 1970s, "Climbing."

We've all seen too many of these heartwarming testimonials not to appreciate the satirical gleam in the authors' eyes. But where is the actual satire? Moony's songs all have their recognizable antecedents. His "Happy Hickory," a dreadfully wholesome musical, bears witness to the influence of Rodgers and Hammerstein. His Bing Crosby ballad, "April in Wisconsin," has the proper air of casual longing. And when in the 1960s, Moony converts to a new sound with "I Found Love," you'll have no trouble identifying that sound as belonging to the Beatles.

But that's about it. The authors don't ever take the next, necessary step, which is to exaggerate, to underline, to exploit the idiosyncrasies in the original models. This isn't satire so much as it is benign emulation. "Songbook" sets up some specific targets and then rather consistently shoots just under them.

Likewise, Moony's picaresque life isn't recounted with much bite, although he certainly seems to find himself at the right place at the right time (Hollywood for the birth of the talkies, Paris in the 1930s, Berlin for the rise of Hitler, London for the rock explosion of the 1960s). Indicative of the level of the writing is Moony's reflection, at one particularly low point in his career: "I felt like emptying the swimming pool and diving off the high board."

If he emerges as a likable fellow, it's largely because Anthony Risoli is a likable performer. Like each of the cast members, Risoli plays several dozen characters in this epic life, but his main responsibility is Moony, and he makes him a rather charming opportunist. Risoli is saddled with one song you wouldn't wish on even Mrs. Worthington's daughter. It's called "You're a Nazi Party Pooper, Jesse Owens," and to make matters worse, he has to sing it as Adolf Hitler. With a stylized zest that is reminiscent of both Charlie Chaplin in "The Great Dictator" and Joel Grey in "Cabaret," Risoli pulls it off.

The others--Terrence Currier, Eleanor Barbour, J. Dan Curry and Barbara McCulloh--may be commended for putting as cheerful a face on things as they do. Barbour's rendition of "Don't Play That Love Song Any More," an especially lovely ballad that is apparently Moony's alone, represents an escalation in the show's fortunes. And McCulloh should probably get a decoration for the bravery she displays while trying to rope the audience into one of Moony's World War II music-hall cheer-ups, the appalling "Bumpity-Bump."

With a full onstage orchestra and a reasonably decorative set that places a white piano center stage and scatters shiny black musical notes every place else, Olney has given "Songbook" a more than even break. Unfortunately, it's not a show to get heated up about--one way or another. Named best musical of the 1979-80 London season, "Songbook" was subsequently rejected by Broadway after a single performance. Both reactions seem excessive.

SONGBOOK. By Monty Norman and Julian More. Directed by James D. Waring; musical direction, Elman Anderson; musical staging, Barbara McCulloh; scenery and lighting, Joseph St. Germain; with Eleanor Barbour, Terrence Currier, J. Dan Curry, Barbara McCulloh, Anthony Risoli. At Olney Theatre through Aug. 8.