THE SPANISH-MADE, air-conditioned bar and toilet-equipped bus - the pride and joy of Cuban tourism - broke down in the middle of a small village in central Cuab. it looked like one of those incidents that can make group travel a nightmare.

Yet, purely by accident, that bus breakdown produced one of the most interesting and moving experiences during a week-long tour of Cuba - only recently reopened to U.S. tourists.

For three hours, while the drivers repaired the bus, Americans roamed the town, which had not seen a North American in years. They visited the school and talked with children and teachers; ate chicken, black beans and rice in the local restaurant, and were invited into homes.

That was the kind of encounter most of us had hoped to experience on the trip - along with ample opportunity to sample Cuba's fabled rum, sun and beaches - while the American northeast battled the blizzard of '78.

Unfortunately, except for that occasion and a few other fortuitous accidents, our hope was frustrated. The tour schedule seemed designed to prevent both taking full advantage of the sun and having any chance to get a good view of what has happened to the people of Cuba after 18 years of Latin-style socialism.

It was a trip in which three full- eight-to-ten-hour days were spent busing around the country. The only stop was for for lunch at one of Cuba's newly built and quite attractive resort complexes, but there was never enough time to really use the facilities. Even the overnight stops and resorts involved late arrivals and early departures, to the point that the trip took on the aspects of a presidential campaign swing rather than a relaxed vacation. Only by refusing to go on one day's tour to the beautiful colonial city of Trinidad was it possible to snatch one poolside respite.

Even with all that busing, we managed to obtain some intriguing glimpses of changes that the Castro government had made - the collectivization of small farms; the replacement of many thatched roof shacks (one veteran reporter of the American South said the ones remaining reminded him of sharecropper homes in Alabama during the 1950s) with large and colorful housing projects; new factories belching smoke in clear disregard for pollution controls that now are required in the United States.

But we rarely had the chance to get off the bus, talk to the people, see the new homes or factories. It wasn't that the guides prohibited it; there just wasn't them.

It was, then, a trip of massive frustrations.

This was the standard tour being offered to Americans for about $800 (all inclusive - meals, rooms and air fare) by Caribbean Holidays, a New York travel wholesaler that has the contract with Cubatur, the government agency that runs the trips inside Cuba. The only difference between our trip - which was sponsored by the Washington Press Club and the Washington Council of Lawyers - and those regularly advertised was the departure from Washington instead of New York.

Which brings up the obvious question - is the tour worth it? The equivocal answer: yes and no. It is the only chance at present most Americans have to see Cuba, and the country is a fascinating, vibrant one. Frustrating as the tour is, it still provides a few glimpses of a socialist experiment that has been largely hidden from American view for almost 20 years.

I'd go again. A friend, on the other hand, says go - but wait till next year when the Cubans have a better chance to get their act in order.

Caribbean Holidays said their Cuban tour has met with great success - more than 80 percent loads each Saturday trip. Officials of the company admit the tour itinerary is an imperfect compromise designed to show Americans more of the island than just the beaches - sun-worshipping Canadian tourists for the most part are merely dumped at a beach resort for their entire stay - and hope next year they will be able to offer alternate itineraries.

To me, though, the real question is whether Caribbean Holidays and Cubatur are willing to modify the tour's schedule to better satisfy the twin desires of Americans who want to go to Cuba - the curiosity about the results of the revolution and a desire to trade the northern winter for Caribbean warmth and sunshine. After all, it sunshine is all the tourists want, there are plenty of Caribbean islands and South Florida resorts offering that product hassle-free.

But Cuba can offer more. It provides a view of Soviet communism, with heavy Latin overtones, and indeed may be the best example of how communism has successful in a Third World country. (When a Soviet diplomat in Washington was told that Cuba seemed to be his country's greatest success in exporting communism to the Third World, he replied, shaking his head, "Oh, but what it costs." The Soviets are estimated to be pouring $3 million a day in direct subsidies to the Cuban economy - exclusive of extra payments for the Cuban troops fighting in Africa.)

One thing should be made clear: The Cuban guides, while proud of the results of 13 years of socialist revolution, are low-key about proselytizing what they consider (and what appear to be) real gains since Castro took over.

Sure, the guides miss few opportunities to discribe improvements and ti insist the country will become even stronger society and economically. But they don't [WORD ILLEGIBLE] over the real shortages of consumer goods, the severe rationing system, the roles in running the country played by the Communist Party and the Committee for the Defense of the Revolution - the ward healers of the revolutions whose offices are seen on almost every block in cities and towns.

There are few indications of anti-Americanism, even at the Bay of Pigs, and - more important - tourists are not subjected to the tiresome, endless and obligatory visits to model collectives, farms, factories, schools, daycare centers and health clinics that are insisted upon by the People's Republic of China in dealing with American visitors.

The problem, then, is how to transmit a better view of Cuban society without massive doses of propaganda; how to give curious Americans a sweeping view of the country without the endless bus rides.

American tourists are clearly welcomed in Cuba, but on Cuba's terms. Tour guides and ministry officials have repeatedly stated they do not want to build the pre-Castro kind of tourism - when 235,000 Americans visited the island in a year - that they feel was based on the twin evils of gambling and prostitution. And, for the moment, they are not encouraging individual visits because Cuba believes it is better equipped to handle groups.

Gary Gonzales, director of commercial policies for Cuba's national Institute of Tourism, realizes there are problems with lines at airports (more about that later), the shortage of good hotel rooms, and a lack of trained guides and hotel personnel.

Castro himself has admitted that Cuba sees tourism as a vital source of dollars to prop up his sagging economy. And Cuban forays in Africa have dealt a setback to the Carter administration's efforts to normalize relations between the United States and the "Pearl of the Antilles."

Part of the reason for the interminable busing is to show off Cuba's new tourist developments, those handsome resorts in the Escombray mountains, in near-Havana seaside towns and in the once-isolated province of Zapata (the area of the abortive Bay of Pigs landing attempt).

These resorts are filled during the summer by Cuban workers, who get a month's vacation a year. In the winter, busloads of Canadian, eastern European and now American tourists fill the rooms."

The hotels are not bad. While the Marazul on the beach in Santa Maria, may not be quite up to class A United States standards, it was pleasant, attractive and clean. Hotel Hanabanilla, overlooking a man-made lake formed from the building of a dam to produce hydroelectric power, was more rustic, but still lovely.

Most striking, however, was a resort where we only lunched but longed to spend more time. It was Guama, a simulated Indian village reached by motorlaunch and spread over 13 islands connected by graceful wooden suspension bridges. The rooms are replicas of the houses used by Indians who lived in Cuba before Columbus landed there.

Each room has its own boat, and according to the Cubans, the lake is stocked with bass. A Texas group, Cuba Tours-USA, Inc., of Houston, offers bass fishing tours to Guama.

The highlight of the tour was Havana. Faded somewhat, it's still a jewel of a city. And it provided the freedom to wander around - poke into shops, look up friends of friends and get some sense of what Cuba is all about.

The hotels are slightly shopworn, but I have stayed in far worse both in the United States and other countries. Havana offers a choice of restaurants - including some of Hemmingway's favorites - which still serve good food. (Make reservations: although food is strictly rationed at the retail level, many Cubans get around it by eating at restaurants, which serve bountiful portions and are crowded with Cuban families.)

The nightclubs are still, going strong. To visit them is like going back 20 years in a time capsule. The Hotel Riviera's Copa Room (the hotel, the Cubans said was once owned by the Mafia) puts on a show featuring women costumed according to 1950 nudity standards and wearing Carman Miranda headdresses. They prance up staircases that burst into light, step-by-step, as the dancers move up them.

The Tropicana, Havana's most famous nightclub, leaves a visitor speechless. The closest equivalent in the United States would be having two or three Super Bowl halftime shows going on at once.

Cubans and tourists alike go these shows. They are not expensive. For about $6 a Cuban can have two drinks, watch the Riviera show and dance.

Cubans on the streets are friendly. They are surprised to find the gringos are Americans, not Russians or Canadians, and anxious to talk - as long as the conversations are light and non-political.

Kids are like kids anywhere - only they appear to be brighter and better fed than in most Latin countries. They follow groups of tourists and surreptitiously ask for chewing gum and pens. If guides or soldiers see this, they pull them aside and quietly scold them.. The gist of the scolding is what will Americans think of the Cuban revolution if children (who in pre-Castro days used to beg for pennies and sometimes hustle their sisters) now follow tourists and ask for chewing gum.

The military presence, incidently, appears far less noticeable in Havana than in many similar countries. Few soldiers are seen on the streets (except Saturday when they are obviously on leave) and police routinely carry pistols, not the automatic rifles sported by cops in some others part of Latin America and in the Middle East.

One of the most interesting sights in Havana is the Museum of the Revolution, housed in what was once the presidential palace, complete with bullet holes from an abortive student takeover when Batista ran the country. It is filled with memorabilia of the Cuban revolution, down to the clothes Castro wore in prison; the typewriter he used to write "History Will Absolve Me," and pictures of "martyrs" of the revolution.

Oddly enough, the Bay of Pigs is lightly treated and it almost appears that the Cuban Missile Crisis never existed.

Outside the museum, treated with the reverence we hold for the Tomb of the Unknown Soldier at Arlington, is a collection of armaments used in the revolution. These include planes, homemade tanks and a van marked "fast delivery" that students used to storm the palace.

There is little to buy in Cuba other than cigars and rum. Both are good, but be prepared; Cuban cigars are not cheap even there - $1 is the average price for an average cigar.

The last day in Havana summed up the good and bad, the frustrations and the joys of touring Cuba in 1978.

The plane that was to return us to Washington, due in mid-afternoon with a new tour group, was going to be hours late because the airport had been closed for a visiting high-level political delegation.

Cubatur was great. Late departure, keep your rooms, extra time for sun, fun and rum. But all that positive feeling disappeared at the airport. It took six hours from the time we left the hotel to actually take off. Bureaucracy, red tape and lines, lines, lines - most of them unnecessary. Lines to check in. Lines for immigration. Lines to get on the bus arrived planeside, an officious Cuban made us head back because the bus door was opened before he gave the word to open the door.

The TWA crew said they had been waiting 1 1/2 hours. "We're trying to do the best we can with these people," said the captain to applause from the tour group. There was even greater applause when he announced the plane was passing over Miami Beach.

Did that chaotic, needless, sweaty period of waiting in lines at the airport (incidently, I am not unusual to badly organized airports, having moved through Cairo, considered one of the world's worst for passenger service, will considerably greater ease) erase all the good will of the trip?

I doubt it. But it did leave questions about wholeheartedly advising others to go now.