Like some of the millions of customers it serves, age and size seem to weigh more heavily than ever on Sears, Roebuck & Co. these days.

During the past decade, the nation's largest and best-known merchant has watched its commanding market share slip, long-reliable profits sag and more lithe competitors breeze past in the accelerating retail race.

To lure back shoppers and boost financial performance, the 104-year-old Chicago-based retail and financial services giant reacted by employing a huge grab bag of retail strategies to regain momentum over the last few years. But those attempts mostly fizzled. Sears recently has reported lackluster Christmas results and laid off more than 20,000 employees. Its stocks and bonds have taken a beating on Wall Street.

So the radars of the retailing business have focused intensely on Sears as its 16-member board of directors, led by Chairman Edward Brennan, gathers tomorrow in Chicago's Sears Tower for a two-day meeting to contemplate problems and search for more effective solutions. The powwow has caused much industry speculation -- strategic sparks may fly, more drastic cost-cutting bombs may be dropped and executive kings may be dethroned, some believe.

And then again, they may not, say many observers, who predict that the slow-moving retail behemoth will opt for more plodding behavior to prune expenses, return to back-to-basics merchandising and wait out the current recession that has hit Sears hard.

A Sears spokesman said the company would not "speculate" on future board actions.

"There are so many scenarios floating around and, because Sears has missed the boat so many times with its customers and then gotten hit by this tough economy, something will have to be done," said Karen Sack, retail analyst for the credit rating agency Standard & Poor's Corp. "But the analogy for fixing Sears is like taking the federal government apart and putting it together as an efficient unit -- it's a mammoth task."

Perhaps change would not be as challenging if Sears were smaller, but it's the nation's largest retailer, with $54 billion in revenue in fiscal year 1989, $31.6 billion of that from retail operations. Arkansas-based Wal-Mart Stores Inc., a retailer only, is a close second at $26 billion and rapidly closing the gap. In addition to the Merchandise Group, Sears also operates large nonretailing businesses, including Dean Witter Financial Services Inc. with its successful Discover Card credit unit, Allstate Insurance, and the Coldwell Banker real estate.

While the financial services subsidiaries have performed strongly lately, the retail end -- famous for everything from Kenmore appliances to Craftsman tools -- has been dragging down profits. Revenue for the Merchandise Group, which brings in more than 50 percent of Sears's sales, grew by only 0.6 percent in 1990 for stores open at least a year. That weak performance, analysts said, is the reason overall profits dropped more than 40 percent for the first nine months of 1990.

"If you don't know where you are going, any road will get you there," said Howard Davidowitz, chairman of the Davidowitz & Associates retail consulting firm in New York. "Sears has let themselves fall behind in the one area that made them famous {retailing} and stopped defining where they are going to customers."

Its many past retailing maneuvers, including adding national brands, changing to a specialty format within stores, switching to "everyday low prices" in 1989 and trying to project itself as highly fashionable, have yielded little reward and even confused customers. Many think Sears must upend the entire business and speed response, letting go of the old way of operating to once again become the retail kingpin it was.

"It just kept creating expectations with all these changes and then disappointing people when they did not work so well," Davidowitz said.

Last year, Chairman Brennan took control of the retail division in an attempt to stop the decline. One of the steps taken was the layoffs, because Sears's overhead accounts for more than 30 percent of sales, compared with leaner operators such as Wal-Mart (16 percent) and J.C. Penney (22 percent).

That may not be enough for the Sears board. "They simply need to reduce costs by huge amounts more -- I would say $1 billion -- to even get close to being back on track," said Wayne Hood, retail analyst with Prudential-Bache Securities Inc. in New York.

The company, which has 863 Sears stores and nearly 900 specialty stores for such items as tires, paint and eyeglasses, also operates stores that are larger than many competitors', and analysts say selling space is not used as efficiently.

Overlapping costs in the massive Sears merchandising bureaucracy is one of its millstones, such as operations at one of the weakest elements -- the legendary catalogue, which has not made a profit in five years. Jobs have been trimmed there over the past two years, but rumors circulate that the entire division may be sold or even shut down completely -- a notion that strikes deep in the hearts of Sears diehards.

Some analysts think the board could lean in this direction soon. "The catalogue is such a basic part of Sears that many there say they could not imagine it closing," Standard & Poor's Sack said. "But it also cannot just continue bleeding."

The board also is likely to focus on Sears's dowdy image and abundance of old-looking stores, compared with more fast-changing merchants such as Wal-Mart and specialty retailers such as Circuit City and the Gap. Even Penney and Montgomery Ward -- Sears's traditional competitors -- have moved in recent years to recast themselves in ways to attract new consumers.

Added to all this, the shaky economy and war in the Middle East have cast a pall over Sears, as consumers shy away from purchases, especially those of big-ticket durable goods that are Sears's bread and butter.

Swifter board action might be spurred by Sears's plummeting stock price, which peaked near $50 in 1989 and closed at $29.75 on Friday. Since Sears stock is held by a large number of institutional investors, including powerful pension funds, pressure is strong for the board to take steps to boost shareholder value.

"Investors are losing patience and that will affect the pace of change at Sears," said Sam Liss, retail analyst at Salomon Brother Inc. in New York.

Sears bonds are also suffering. Last summer, Moody's Investor Services Inc. lowered the rating on some company debt because of lackluster results in the retail area, which makes it more costly for Sears to borrow money. In January, Standard & Poor's did the same, blaming the still-weak retail results and "failure, to date, of the company's revised merchandising strategies to address the problem."

With all this, some analysts are suggesting that the board may even go as far as junking the top management, including Brennan, though many think that is a last resort if results do not begin to improve.

While the challenges are great, many think Sears -- still profitable, asset-rich and carrying none of the disabling debt that burdens other major retailers such as R.H. Macy & Co. -- has the potential to do just that.

"Retail is a mature industry in the process of a massive shakeout with a lot of middle guys that competed with Sears collapsing," Davidowitz said. "Sears could step in and capture back what it lost."

Standard & Poor's Sack agrees. "Sears was America, apple pie, motherhood. It still has a name and it has meaning -- that can count for a lot when used right," she said.

But getting it right may have been something that Sears should have begun doing long ago, according to Sack and others.

"It's so competitive and there has been so much bad publicity for Sears -- and it's so big everybody knows about it," Sack said. "When it gets to the point where too many people are saying 'This is not the Sears of my childhood,' it may be a case of too much to do too late."