Northwest Airlines, its problems spotlighted after the disaster in Detroit, reaffirmed yesterday that it is moving to overcome an employe work slowdown and a spate of minor vandalism to its ground equipment.

Northwest officials said the airline has gone on the offensive against what it calls nuisance vandalism by offering a $25,000 reward for any information leading to the cause of the trouble.

"We believe someone's roommate or lover will turn them in for $25,000," said Redmond Tyler, a spokesman for Northwest Airlines. "We are producing desired results."

The vandalism, which the airline said has been increasing, has included keys lost to aircraft parked in hangars, disconnected wires and tires found slashed or with the air let out of them -- problems that delay aircraft but do not affect safety. Tyler said most of the incidents have occurred in Detroit.

Originally, the airline offered a reward for $5,000, but it increased the amount last month.

Northwest also reported that it is battling what it considers to be a work slowdown by its mechanics by contracting out some of its maintenance to other airlines. Outside of this diversion, Northwest performs maintenance at Minneapolis-St. Paul and in Atlanta, where engine repair is done.

The airline has not attributed any of the vandalism problems to its employes, and labor leaders have scoffed at the idea that mechanics would sabotage planes.

"It would take a complete idiot . . . to sabotage the airplane you and your family may be traveling on," said Guy Cook, president and general chairman of the International Association of Machinists & Aerospace Workers Air Transport District 143 in Minneapolis.

Some of the passengers who arrived at Dulles International Airport from Detroit after the crash of Northwest Flight 255 on Sunday, however, wondered whether they were victims of luggage tampering.

Jane Britt, a public relations executive who lives in the Washington area and was on the Detroit-Dulles flight, said passengers' luggage that came through the baggage claim area had been badly damaged.

Britt said her bags arrived intact, but one suitcase "looked like an elephant had stepped on it," while clothes had been pulled out of garment bags and a brown shoe was moving solo on the baggage carousel.

"Even on a night with a fatal crash, it looked like they had someone fooling around with the bags," said Britt.

The airline said yesterday it does not respond to news media inquiries on individual passenger problems.

But Northwest is making some inquiries of its own on the source of an increasing number of consumer complaints to the government about its service.

The airline has filed a Freedom of Information Act request with the Transportation Department to try to find out if complaints being filed are legitimate ones. Last month, Northwest jumped to second in the rankings of airlines with the most customer service complaints.

Staff writer David S. Hilzenrath contributed to this report.