For most of its 16 years, the General Electric Co. steam turbine plant near Charleston, S.C., was one of the company's gems.

It was a modern, profitable operation, blessed with a productive work force and an able management that worked constructively together, for the most part.

But next June, GE will close the plant down, laying off 350 workers, because the steam turbine components from the plant are no longer needed by a stagnant electric power industry.

To the employes, the demise of the plant, like others all over the country, is taking another bite out of this country's middle class, which supplies most of the country's factory workers.

At its peak, the plant employed 1,200 production workers whose enviable wages and benefits placed them at the top of the blue-collar economic ladder.

"We were looking at average wages at $10 an hour," says Carnell Gathers, president of the local United Electrical Workers union at the plant. "The benefits are terrific. I don't know of any place in the Charleston area that can duplicate what we've got."

Or had.

According to Gathers and other UE officials, the laid-off GE workers are taking jobs in the area that pay $5 to $6 an hour less than they were getting.

"This is a national problem," said a bitter UE member John Burns. "National awareness has to be raised. Somebody has to draw an industrial paycheck . . . ," he said. To Burns, the closing of the Charleston plant symbolizes a devastating shift in employment from skilled manufacturing employment to lower-paying service work -- a shift from making complex industrial products to making hamburgers, as he and others put it.

The plant closing is obviously a tragedy for Charleston. But is it evidence of a national problem?

Economist Robert Z. Lawrence, senior fellow at the Brookings Institution, argues that despite such visible plant closings around the country, "the bottom isn't dropping out of the middle."

Lawrence's evidence, reported in the latest edition of The Brookings Review, is based on a comparison of the distribution of income among Americans working full time in 1969 and in 1983.

In 1969, middle-income wage earners made between $94 and $197 a week. In 1983, the range was $250 to $499 a week, in his analysis.

The analysis shows only a slight downward shift away from middle to low income over that period. In 1969, 20 percent of full-time workers were upper income, 50 percent were middle income and 30 percent were low income. Fourteen years later, the breakdown was 21 percent high income, 46 percent middle income and 33 percent low income.

Behind those overall numbers, however, some dramatic shifts have occurred in specific industries and among specific groups.

While the declines in the middle were widely spread among various industries, they were particularly heavy among workers like those at Charleston, Lawrence concluded, adding, "the dropoff was steeper in goods production than in the economy as a whole, and it was especially marked in such high-wage sectors as mining, durables manufacturing and transportation." The proportion of younger workers with middle-income wages dropped sharply. And there was a large decline for males and corresponding gains for females.

But these shifts don't reveal the collapse of the middle class, Lawrence argues. It is simply wrong to generalize about the nation's overall economic condition from losses from plant closings in particular communities, because the Charleston story doesn't tell us about the creation of new jobs.

"If a job in the automobile industry in Detroit is replaced by an insurance job in San Francisco that pays the same salary, the distribution of income will not change. However, the auto worker's life will," Lawrence said.

In Charleston, the GE workers -- holding little hope for retraining or relocation -- have fought a novel, desperate campaign to avoid that fate by keeping the plant open and turning out some other industrial product. If there were too little demand for steam generators, the plant could be used for something else -- pollution control equipment, high-technology medical systems, prefabricated bridge and tunnel sections, for instance, the union said.

The employes' first appeal was to GE, to get the company to move some other GE product into the Charleston plant. They enlisted the Rev. Jesse Jackson, other clergymen and local politicians to try to push GE in that direction, but GE said no: there was no other product that would fit the plant and the company wouldn't take work away from other employes to save the jobs in Charleston.

GE -- one of the nation's strongest manufacturers -- is cutting back its operations to concentrate on the most profitable and promising. In the years ahead, it sees slower economic growth and tougher competition, particularly from abroad, and the Charleston plant is a casualty of that new reality.

The question that Lawrence's otherwise persuasive analysis doesn't satisfactorily answer is whether the kinds of jobs like those at the Charleston plant -- with their relatively high wages and benefits -- will be replaced by other, equally rewarding jobs in the era of tougher competition that GE sees ahead.