July 12, 1984

After nearly a decade of selling off unprofitable business lines, closing plants and investing heavily in new lines of aerospace and military products, the Singer Company appears to have completed what some analysts call one of the most thorough corporate restructurings in recent memory. The changes have been slow and agonizing. What started in the mid- 1970's as a gradual retreat from its old-line sewing machine business has become, during the last five years, a huge overhaul of Singer's corporate identity. ''This is a company whose whole culture was built around the sewing machine,'' Joseph B. Flavin, the company's chairman and chief executive, said in a recent interview at Singer's headquarters here. ''As hard as we tried, that couldn't be changed overnight.''

The Government said today that air bags or automatic seat belts would have to be provided on all new passenger automobiles sold in the United States in five years. However, this requirement would be rescinded automatically if state legislatures representing two-thirds of the population required that occupants of autos use seat belts. The decision, after 15 years of controversy, was applauded by the auto industry but criticized by insurance companies and consumer activists. The reason for the opposition was the condition regarding state laws allowed by the Transportation Secretary, Elizabeth Hanford Dole. Law Passed in New York So far, only New York State is close to a law on seat belts. On July 2, the Legislature passed a bill that would require drivers and front-seat passengers to wear seat belts by the end of the year. Governor Cuomo said last week he was awaiting action by the Transportation Department before he dealt with the bill, but his staff said he was expected to sign it this week.

A report in New York Day by Day yesterday on groundbreaking ceremonies at Steeplechase Park in Coney Island misattributed a quotation. It was Comptroller Harrison J. Goldin who said, ''We're not doing the Parachute Jump yet, but that's next.''

Walter F. Mondale says he will not run on a ticket with the Rev. Jesse Jackson because of deep differences between them. Mr. Mondale made the remarks about Mr. Jackson, who complained Tuesday that he had not been considered for the Vice Presidency, in an interview to be broadcast Thursday on the ''CBS Morning News'' and made available here tonight. ''I intend to pick the best person I can find who's compatible, whose selection speaks for my vision of our future, and there are sufficient differences between Reverend Jackson and myself that I can't do that,'' Mr. Mondale said in the interview, excerpts of which were broadcast this evening. 3 Key Differences Cited In Minnesota, Mr. Mondale's press secretary, Maxine Isaacs, summarizing the former Vice President's interview, said the differences between the two men involved Mr. Jackson's call for a Palestinian state, relations with the Palestine Liberation Organization and cuts in the military budget. In Chicago, Mr. Jackson said that he accepted as ''honorable'' the reasons Mr. Mondale did not consider him as his running mate and that Mr. Mondale's selection process was ''good on balance'' and even ''commendable.'' (Page A16.)

Since martial law was imposed in Poland in December 1981, letters smuggled out of prison by Adam Michnik, an adviser of Solidarity, have helped sustain hope in the outlawed movement. Mr. Michnik is scheduled to go on trial Friday. It is a trial that the authorities tried to avoid by offering him freedom and the right to go abroad. It is a trial that Mr. Michnik demanded. The smuggled letters by Mr. Michnik, a 38-year-old activist, have been copied by hand, typed, mimeographed or printed in clandestine shops. They have been widely read and discussed.