Mighty America gives Cuba a lesson in can-do efficiency? Think again. The Milwaukee Symphony's weekend adventures on this embargoed island became a drama with several happy endings, but the opening acts were tortured indeed. If things went wrong, don't blame Havana, whose officials were like benevolent spectators to a chain reaction of self-induced mishaps.

The good news should come first: a morning concert on Friday for radiant and clamoring children and an evening event for equally rapt adults and young musicians, both at the newly restored 800-seat Teatro Amadeo Roldan. Perhaps concerts should be judged not simply on how well the participants play but on how musicians and audience members are joined. The expressions on listeners' faces at both concerts told a story of intense pleasure. The whispering was almost welcome, for these were people excitedly exchanging observations on the orchestration of Bernstein's ''West Side Story'' Suite, or the octave technique of Eduardus Halim in Liszt's E-flat Piano Concerto.

The trip had been brewing for two years, inspired by a softening of cultural barriers between two countries and preceded by the visit of a youth orchestra from New England the year before. The idea of providing top symphonic entertainment to the Cuban people was always present, but board members accompanying their charges made no pretense of the Milwaukee's major mission: to provide an international splash of publicity for a reputable American orchestra with a relatively low profile. The symphony had long been scheduled for a concert at the Kravis Center for the Performing Arts in West Palm Beach, Fla., and so Cuba became a scheduled 45-minute jump by air charter. Red tape was penetrated, voluminous visas assembled, and bravely on Thursday the planes set off, one of them at least.
The other, carrying the orchestra's larger instruments, sat quiescent in Miami, victim of malfunction. Hours later a replacement plane, laboriously reloaded, took off for Havana, but it lacked the revised paperwork and bore tail numbers unknown to Cuban air-traffic control, which denied the newcomer air space and strongly suggested it return to where it came from. Properly documented but its contents still not cleared by customs, Milwaukee's musical cargo arrived toward midnight and spent the night within the spartan confines of the Jose Marti International Airport.

This proved something of a problem for the evening's scheduled open rehearsal. Musicians, already dazed by a two-hour-plus flight delay and relaxed by the wondrously green tequila drinks passed out at a welcoming lunch (by that time dinner), showed up onstage without enough instruments but at least capable of some self-described ''meet and greet'' with assembled Havanans.

By 10:30 on Friday morning, the youth concert's scheduled starting time, the instruments were approaching, but had not arrived. It was agreed that rather than examining double basses, bass drums and mallet percussion instruments at the airport, a customs officer would ride shotgun and tick off items as they came off a truck into the stage entrance. The panoramic view was fascinating: children streaming in by the front entrance; large musical devices being manhandled in the same direction around the corner. No one seemed to mind the hour-and-15-minute delay, punctuality being perhaps more a North American than a Caribbean imperative.

There was plenty to do during the wait. If Havana itself is battered, its children are up to date. Shining and well-groomed in their red pinafores, yellow skirts and gleaming white blouses, they seemed genuinely thrilled by the 500 individual letters from Milwaukee schoolchildren. Happily armed with the orchestra's elaborate program books, they besieged backbench violists and bassists, who may have been signing autographs for the first time in their lives. Across the street from the theater, one violinist stood and played, ringed by eager 8-year-olds in red.

Inside, his colleagues, some gastrically devastated by an unwise trip to a restaurant across the street from the wonderful old Hotel Nacional, summoned their faculties, accompanied the splendid narrator Hector Quintero in Prokofiev's ''Pedro y el Lobo'' (''Peter and the Wolf'' to you), and ripped handsomely through the Bernstein, whose Latin influences were not lost on these listeners.

Afterward the National Cuba Youth Symphony sat onstage and briefly played. Its director, Anarelys Garriga Sosa, said the players, ages 8 to 14, were drawn from schools around the country. Many of their music teachers had come from Soviet-bloc countries or were trained in them. The economic tribulations in Cuba since the breakup of the Soviet Union have been well documented but extend also to a lack of school instruments in working order. On the other hand, Diana Haskell, the Milwaukee's acting principal clarinetist, reported that her brief session with two colleagues from the National Orchestra of Cuba showed musicians well trained and equipped.

''They play with a wonderful, soulful style and their instruments may be better than mine,'' she said.
The National Orchestra, about 60 full-time musicians, is fed by lesser municipal orchestras and plays about 25 times a year, said two young players, Carelys Carreras Camporredondo, 23, and her teacher, Antonio Dorta Lazo, 29.

Despite its breathtaking dilapidation, Havana is a city of enormous charm. Parks, beautifully vegetated, are everywhere. Some restoration is taking place. Streets are as clean as can be expected given the peeling paint, broken windows and shedding plaster. Old mansions -- many are like palaces -- retain a crumbling grandeur. Cars a half-century old cruise the streets, giving the sense of a time warp. Uniformed police are seen everywhere and assuredly many more are unseen.

With a sweet patience, people in battalions crowd bus stops waiting for the next ''camel,'' an elongated split-level vehicle carried on a flatbed truck and said to accommodate 250. This is a deeply troubled country, but there is an evident pride in Cuba's independent stance and a wistful friendliness toward America that does not exclude anger over the dispute surrounding Elian Gonzalez, the 6-year-old Cuban refugee whose presence in the United States is being debated after he survived a ocean journey to Florida that took the lives of his mother and 10 others. The dollar is the currency of choice, preferably fives and tens.

Friday night's concert was touching, the program beginning with Liszt and ending again with ''West Side Story.'' Horn players quelled their overactive stomachs and roared out the great horn passages of Strauss's ''Don Juan.'' Three encores included Gershwin's ''Cuban Overture.'' The Milwaukee's strings showed a European soulfulness and a corresponding European mushiness in ensemble. In American repertory, however, the orchestra turned very American, with a confident bite given to Bernstein's constant meter changes. Whether to attribute the fuzzy moments to collective exhaustion is hard to decide, but the orchestra seemed very well led by its conductor, Andreas Delfs, 40, a sound musician with precise conductorial control.

The Milwaukeans are home by now, basking I am sure in their city's approval and the heavy attention of international television crews. They must also be totally exhausted. Their tour seems to have been planned with the thought of everything going right. It didn't. Rarely in music will so much good and bad have been so tightly packed into two and a half days.