Hajime Karatsu cannot repress a smile when he considers how his professional life as an electronic communications expert has come full circle.

Back in the 1950s, when Japan's economy was a primitive one, he was a leader in bringing the widely admired techniques of American industrial management to Japan. Like many others then, he especially was intrigued by the high productivity of American plants and the quality-control methods used to minimize defective products.

Now, in a curious reversal of roles, he is preparing to teach Americans how the Japanese do the same things better.

Karatsu and several other prominent businessmen have formed a new Association to Encourage the United States, designed to help American companies revive productivity, make better products and regain competitiveness.

They are a bit squeamish about teaching the former masters and worried they'll be thought presumptuous. Their group's first title was Association to Rescue the United States, but they decided it was rather immodest.

"We don't want to do anything too aggressive, too audacious," said one architect of the plan, Masaichiro Muto. All they want to do, he added, is suggest ways in which the American factory could produce more goods for less at higher quality and bring the world's biggest economy out of the doldrums.

In October they intend to map out detailed plans for producing instructive films and holding seminars for U.S. businessmen and workers. They will explain how modern scientific management techniques were learned in the West and then adapted to Japanese industries, which have become the world's most productive. They will stress the famous quality-control circles, which enable factory workers to take part in management decisions and which Japanese regard as the most vital element in their successes.

Their motive is not entirely one of good will. They think Japan will suffer if the U.S. economy continues to decline and fear the consequences of Japan's most important ally and trading partner surrendering its world leadership. They gloomily believe the United States is heading in that direction.

"The United States must remain strong to keep the peace in the world," said Karatsu, managing director of the Matsushita Communication Industrial Co. "We want the United States to continue to be the stabilizing power in the world."

Japan has been teaching its productivity secrets to an eager and growing clientele of foreign businessmen for several years. Many American corporations send teams here, and several -- such as Lockheed -- have incorporated quality-control circles into their plants. Japanese plants that have set productivity records are now meccas for European and American management. Foreign teams pay an average of 170 inspection visits a month to Nissan Motor Co.'s plant in Zama.

Many visits are arranged by the world-famous Japan Productivity Center, of which Muto is managing director.

Karatsu's career, as learner and now teacher, symbolizes the turnabout from the days when Japan was importing techniques and ideas in a desperate attempt to get its postwar economy moving.

His education began in 1951 when he was with the government's fledging communications company that was trying to introduce a modern telephone system. An engineer working with the American occupation forces became so outraged with the poor quality of equipment that he virtually ordered Karatsu to impose some quality controls.

That was when Karatsu started hearing about the famous W.E. Deming, then the high priest of quality control. He studied Deming, was impressed and in 1958 paid a visit to several American plants -- auto companies in Detroit, National Cash Register in Dayton, United Air Lines. "They were all very excellent," he recalls now. "You had so many things that were very good. You must polish it up again."

But recent visits to American factories left him depressed with examples of shoddy production and low worker morale. In one auto plant he smelled marijuana smoke on the assembly line, and it astonished him. "That would be incredible in Japan," he said.

The group tends to be politely critical of American management ways, considering them rather authoritarian.

And, after meeting with American business leaders recently in Washington, Muto came away feeling they were not very interested in modernizing management techniques. He found management and some labor leaders insisting that improving productivity was solely a management problem that did not involve the workers.