A U.S. Department of Transportation employee inserted $3 into the Farecard vending machine at Metro's new Stadium-Armory station Thursday, pushed the buttons as the machine instructs and found himself in possession of a ticket for San Francisco's Bay Area Rapid Transit (BART).

In another incident, Scott Spiegel, a Washington resident who had just retured from a trip to San Francisco, took the BART card he had purchased there, inserted it into the Farecard gate in Washington's Metro Center station and was admitted, no questions asked.

"I can explain about the machine vending the BART card," said Metro's Paul Johnson. "But our machines are not supposed to accept BART cards."

Johnson's explanation will come later in this account of some of the things that are going wrong in the final days before Metro officially opens its new "blue line" Friday. The line will run between Stadium-Armory and National Airport.

Metro has been running trains on regular schedules throughout this week on the blue line to test the system and equipment and give free demonstration rides to the public and VIPs.

There have been some difficulties: doors on the new Metro cars stick, so the cars won't go.A car gets overloaded and refuses to move. Signals at both terminals have been balky, slowing service.

"We're getting better every day," said Ralph Wood, Metro's director of operations. "We've got a lot of new equipment out there and we're shaking it down as quickly as we can. It would be nice to have a little move time, but we're going to be ready July 1."

While Wood is worrying about trains and signals, Johnson is worrying about Farecard, the wallet-sized, magnetically encoded ticket that Metro users must buy to ride the subway after Friday.

Since June 13, they have had the option of buying Farecard or using the old exact change process.

Farecard gates and machines are sold by Cubic Western, which also has provided the equipment for BART's fare system. As the new Farecard vending machines have been installed and tested at Metro's stations, BART cards, similar in appearance, have been used in tests.

The Stadium-Armory station machines aren't officially open yet. The DOT employee found one working, however, when he took a free ride on the train and decided to buy the card. BART test cards were still in the machine.

That doesn't explain how Scott Spiegel got in. "BART cards are supposed to be encoded differently and are not supposed to work here," Johnson said. "I'll just have to ask some questions about that."

For the most part, Johnson said, people have had little trouble with Farecards. They do not work well when crumpled or wet, however, and, like any magnetic tape recording, must be kept away from magnets.