NO, my broker is not E. F. Hutton.

But if you want to eavesdrop on some of Hutton's investment advice, there's at least one cash management secret that still hasn't made the headlines.

Along with writing multimillion-dollar rubber checks, Hutton took advantage of this other little quirk to confuse bank computers and make extra money.

The technique involves messing with those funny square numbers on the bottom left side of checks. Those numbers are printed with special magnetic ink so they can be read by computers using a process called MICR. Pronounced "My-Cur" by bankers, the initials are short for Magnetic Ink Character Recognition.

Sometimes the MICR numbers on a check get smudged or aren't printed properly, and the computer can't read them. When that happens, the computer kicks out the check for hand processing, which takes an extra day or two.

A day here, a day there, the float flows on, providing an interest-free loan until the check finally clears.

At Bank of America in California, as many as 50 percent of E. F. Hutton's checks were "nonreadable items," according to a memo made public last week by congressional investigators. At Chemical Bank in New York, "improperly coded items" at one point produced an overdraft of $48,668,537 in Hutton's account, records of that bank disclose.

Hutton executives insist this was all an accident, but neither the bankers nor the House Judiciary subcommittee headed by Rep. William Hughes (D-N.J.) are convinced.

Bank records obtained by subcommittee investigators show the bankers had been having trouble with Hutton checks klutzing up their computers for years. The memos show Chemical Bank's difficulties began in 1980, and Bank of America "has had problems with Hutton's checks since the l970s.

"These problems have recently intensified; Hutton's checks are increasingly unreadable," complained Christopher T. Mahoney, a Bank of America vice president. In a May 7, 1985, memo urging his superiors to clamp down on Hutton, Mahoney noted that "Hutton has admitted to deliberately seeking to take advantage of check-clearing delays. The prosecutor told me that this included deliberately tampering with the MICR on their checks in order to obstruct presentation."

Hutton's response was to blame the problem on badly printed checks and promise to get new ones. "New checks should be in all branches by year end," the company told B of A in 1980. Five years later, Hutton checks still were falling through cracks in the computer system.

There is no indication so far that the case of the messed-up MICR is as big as the check- kiting scam that led Hutton to plead guilty to 2,000 felony violations and pay a $2 million fine last month. Nor is there any suggestion of criminal violations.

But regardless of its legality, the matter casts more doubts on Hutton's business practices. It is an insightful anecdote about the corporate culture of a firm whose success depends on that most fragile of commodities -- public confidence.

While Hutton executives were concocting their schemes to buoy the company's profits by playing the float, they were simultaneously sinking Hutton's credibility.

The waves of new disclosures that have been spreading since the splash of the indictment are eroding confidence not only in Hutton but also in the banks it was dealing with and the regulators who were supposed to be policing the banking and securities industries.

Anyone who has ever had a check bounce because a deposit was a day or two late in clearing can be justifiably livid about the way banks handled multimillion-dollar overdrafts on Hutton's account.

When First American Bank of Washington caught Hutton kiting checks in 1982, no one called the cops or pressed criminal charges. First American simply told Hutton to pay up and play by the rules, and then the chairman of the board wrote Hutton a thank-you letter.

Thanking someone when they stop stealing from you requires somewhat more civility than most people can muster in such situations. But in a letter disclosed by the Hughes subcommittee last week, then-First American chairman Francis Addison told Hutton President George L. Ball, "You can be proud of your officers who corrected this problem and reinforced our faith in the American business system."

Faith was not so easily restored at Riggs Bank, which had overdraft problems with Hutton at about the same time. After being jerked around by Hutton for several months, Riggs fired off a registered letter telling Hutton to take its money elsewhere.

Nor is faith in Hutton helped by the memos written in 1982 by Perry Bacon, manager of the Hutton office at 1825 I St. Defending what he called "bogus deposits," Bacon said: "Our objective is not to steal money from the banks. Whatever the bank may have lost, we have enjoyed a greater profit." He assured skeptical colleagues that "our activities are generally consistent with and encouraged by the firm."

The growing implication that dubious cash management practices were standard operating procedure at Hutton casts further doubt on the decision by the Department of Justice not to take criminal action against individual Hutton executives. The continuing disclosures also put pressure on the Securities and Exchange Commission to use its authority to conduct its own investigation of the securities law implications of the Hutton matter.

The claim that top executives didn't know Hutton was windsurfing on the float is little more than an exercise in deniability. Considering the complexity of the interest-generating schemes, the importance of interest income to Hutton's profits and the intense competition among divisions to improve interest earnings, it's hard to believe no one at the top asked where all that new money was coming from.

Even if they get off easy with the government, Hutton and its brokers deserve to suffer in the marketplace when customers decide they don't want to do business with people who play these kinds of games.

Already, the slogan that helped build Hutton's reputation is being turned into a nasty put-down as Washington's one-liner of the week: "When E. F. Hutton talks, people lose interest."