Most of Metro's subway workers and some of its bus drivers returned to their jobs yesterday but their efforts were not enough to save Washington area residents from another day of wretched traffic jams as the transit strike rolled on.

Metro officials were quietly hopeful that the back of the strike was broken when they got the subway completely in operation at mid-morning, but bus drivers in all but one of the area's eight garages were not impressed and continued to stay away from work.

It was 8 a.m. before Metro announced that the subway's Red Line from Silver Spring to Dupont Circle was open. By that time most area commuters had already committed themselves to driving to and from work.

As a result, both the morning and evening rush hours were a mess yesterday, and the outlook for today was still uncertain. Metro said the subway will run on schedule today, but would not predict how much bus service will be available.

A firebomb was tossed at a bus at the intersection of Delaware Avenue and M Street SW yesterday, but no one was injured. Union and Metro officials also received several reports that the automobiles of working bus drivers had been vandalized.

Security was heavy and visible throughout the subway system and outside the bus garages. D. C. police said they had spent more than 4,000 hours and $50,000 on overtime since the transit strike became serious last Thursday.

Late yesterday, at the direction of U. S. District Judge Thomas A. Flannery, officials of Amalgamated Transit Union Local 689 called their first press conference of the strike to announce that special security precautions had been taken for the protection of bus drivers and that it would be safe to return to work. The union local has officially disavowed responsibility for the wildcat strike.

Rodney Richmond, secretary-treasurer of the local, said that police officers will be present at all Metro garages and at the entry terminals that subway employes use to get to work. In addition, Richmond said, plain-clothes police officers will rove both the subway system and the bus network.

While the issues of the strike were being played out in federal court, the bus barns and the subway tunnels, area residents were trying to cope.

The only bus division operating at full strength was Arlington's, which serves North Arlington and western and northern Fairfax County. Most of those buses drop people at the Rosslyn Metro station, where they ordinarily would catch the Blue Line into Washington. But the Blue Line did not begin running until about 10 a. m.

People jammed into Rosslyn to ride the pathetically few M6 buses that cross Key Bridge into Washington. Many of them, like Howard Whipple, who works for the Federal Maritime Administration, even drove to Rosslyn to catch the M6.

"I think I got the next to the last parking space," said Whipple. "I'm already an hour late."

John Davidson was also standing in line for the M6. "I can't decide whether to wait for a bus or to walk to my job," he said. He looked at the bumber-to-bumper traffic and set off on foot. "This way, if I'm late, I'll have an excuse," he said.

Many cars were packed out on the freeways. Shirley Highway, whose exclusive express lanes were opened to everbody, had an enormous back-up both morning and evening. Any major artery leading to a bridge had major problems.

The evening rush, despite the return of the subway, was one of the worst outside a snowstorm in recent years. An accident on the 14th Street Bridge kept incoming cars backed up, and traffic was stacked solid in the city's West End. A number of fender-benders made it worse.

Metro managed to get 208 buses on the streets during the morning rush hour yesterday and 186 during the evening-a far cry from the 1,500 or so that rush hour requires. There was virtually no service to the Maryland suburbs, south Arlington, Alexandria and southern Fairfax County, and in the District of Columbia.

The subway carried about one-third its normal load after opening late, according to rough estimates from Metro personnel.

Although the strike ostensibly began as a protest over Metro's withholding of a cost-of-living pay increase, the thing uppermost in the minds of strikes interviewed yesterday seemed to be amnesty from Metro disciplinary measures and court actions.

Adding to that problem were confusion over the number of strikers who actually face such disciplinary actions and several reports, which spread rapidly among strikers, that some returning workers had been greeted with suspension notices by Metro supervisors.

"I think there is probably some accuracy to that," said Peter Sheehan of Metro's labor relations office. "Generally, if a guy comes in an hour late, he is suspended in the normal course of things . . . It might not even be strike-related."

The confusion over the number of suspended employes started Thursday night when Nicholas J. Roll, Metro's assistant general manager for transit services, said that about 180 employes had been suspended. That number became gospel and was widely repeated, as recently as yesterday morning in a radio broadcast by Metro spokesman Cody Pfanstiehl.

Yesterday afternoon, Metro lawyers told Judge Flannery that only 23 employes had actually been suspended. "Twenty-three?" Flannery asked. "I thought Judge Oberdorfer told me more." (Flannery was taking over the Metro strike case from Judge Louis F. Oberdorfer.)

Peter J. Ciano, one of Metro's attorneys, explained that the number 180 referred to the total number of people Metro planned to name in court papers it filed the day the strike began. Only 123 of those names were actually listed because Metro ran out of time before filing the papers.

Before the court signed Metro's request for an emergency order banning the strike and naming the 123 individuals, only 23 strikes were actually suspended, Ciano said. Of those, only six have received the formal written notice that is required.

"No other suspensions are going on," Ciano said. "The remaining employes we would welcome back."

Flannery suggested that the names of the 23 strikes who were suspended be posted so Metro workers would know whether they were "walking into a suspension," as attorney Lawrence Spieser put it. Spieser is representing some of the individual defendants.

Speiser tried for a second time yesterday to amend the court order originally issued by Judge Oberdorfer so as to stop the strike in such a way that Metro disciplinary action would also be stopped-amnesty, in other words. For the second time, such a motion was denied.

Metro and Local 689 reported that they have selected an arbitrator to hear the cost-of-living pay issue argued this Thursday. The arbitrator has agreed to the court's order to resolve that issue by Aug. 6, and it could be resolved by the end of this month, the court was told. Before the strike, resolution of that issue was promised no earlier than the end of August.

Three Metro employes are scheduled to appear in court today to show why they should not be held in contempt for violating the back-to-work no-picketing order.

Flannery had marshals check several vital Metro locations yesterday and then report in court that they appeared to be safe.

There appeared to be no actual picketing at any Metro locations yesterday but groups of drivers milled around garage entrances and were every bit as effective as a picket line would have been.

"I came here today with the intention of working today," one driver said at the Southerneastern garage. "If I try to pull a bus out of the garage, 20 or 30 guys will be standing there. What am I supposed to do? Run 'em over?"

"I don't want to get into problems with my car," another driver said. "Besides I have to face all these guys every day."

At about 7:20 a.m., the word spread that a few drivers were ready to take buses out. A Metro transit police car showed up, several supervisors walked to the open front of the garage and two drivers stepped into the buses in front of the line.

All the striking drivers, who had been standing in little groups along the block across M Street SE from the garage, moved close to the sidewalk on their side of the street, taunting the drivers: "Come on out. What's the hold-up? Come on out."

The scene went on for nearly 10 minutes as the drivers in the buses waited and the strikers remained across the street. Finally, two buses, then a third, pulled out. They were back at the garage within an hour.

The driver of one said he had been driving for 14 years and took his bus out because "within myself I felt I should go to work." The reason? "Need, need," he said. He has six children at home.

Metro has contended from the beginning that a few people perhaps 100 - are providing the intimidation necessary to keep the rest of the workers away.

The firebombing occurred just a few blocks from the Southeastern garage. A bus from another garage, Northern, was carrying two passengers when the firebomb hit it and bounced off the roof, into some bushes, according to D.C. police. No one was injured.

But driver James W. Yates Sr. said he "heard a noise like a bottle hitting the bus and at the same time a small explosion, like gunfire." The bomb ignited the bushes in front of some townhouses on the east side of the street.

Yates said he took his bus out at 4:16 a.m., unsure whether the strike was still on or not, and afraid not to work in case others did. "I didn't want to refuse to go out and get in trouble." he said.