The final dress rehearsal for the NFL's new instant replay system wrapped up this weekend as teams completed their preseason schedules. In general, it has received decent reviews, with several exceptions, including a glaring mistake in last Monday night's nationally televised game between San Francisco and Oakland.

In August, it's a ho-hum error that will be used as a training tool. In December, with a playoff spot on the line, a similar botched call could be a full-blown disaster.

"I would say it's working about the way I would have expected," Jerry Seeman, the NFL's supervisor of officials, said Friday. "We anticipated that the preseason would provide a laboratory setting from a technological standpoint, the communications system and things like that. We want to get all these things under our belts and deal with them now, before they become a problem."

Going into the final week of the preseason, replay had been used in 47 games, with 43 reviews of plays, including 34 challenges by coaches. Five of the challenged calls were reversed after the referee watched the replay on a sideline monitor.

The new system, which allows each head coach to challenge two calls per game, also allows for a "replay assistant" in a press box booth to call for replays in the final two minutes of each half and overtime. If a coach's challenge is not reversed, the team loses a timeout.

Entering the final week of the preseason, nine reviews of plays were mandated by the replay assistant, with two of the calls reversed, again by the referee on the field. No timeouts are involved if the replay assistant calls for a review.

The average time of each review had been about one minute, according to Seeman. The total delay in the game, a major concern of league owners, has been 2 minutes 33 seconds from the time a challenge was signaled by a coach until the next snap of the ball.

Replay was used in the NFL from 1986 to 1991 before owners voted it out. The old system, using somewhat slower videotape technology, led to interminable delays in games, a major reason it was abolished. But after a number of controversial plays late in the 1998 regular season, as well as the availability of far more sophisticated and swifter digital technology, league owners voted 28-3 last March to bring it back for one year.

The system covers a variety of plays in three main areas--sideline, goal line, end zone and end line plays; passing plays and other detectable infractions, such as a runner ruled down not by defensive contact, and the number of players on the field. Potential penalties like holding or pass interference are not covered under the new system.

Last Monday night, a Raiders receiver caught a pass, took several steps with the ball and went down, with the ball coming loose. The 49ers recovered, but the official on the play ruled that the receiver had been down by contact, a call that--right or wrong--automatically nullified the fumble.

The replay seen by the national audience on ABC indicated the ball did come out and should have been ruled a fumble. But because the official had signaled the play dead on the field by ruling the receiver down, this was a play that was not reviewable under the new system.

The biggest mistake was made by the referee, Phil Luckett, the man who botched the coin toss last year in Detroit on Thanksgiving Day. Instead of consulting the official who ruled on the player being down by contact, Luckett went to the sideline and reviewed the play. Once he saw that the official had ruled the receiver down, the Raiders retained possession.

"He never should have gone to the monitor," one NFL executive said. "The bottom line is that the call came out all right. But it just looked sloppy, and TV had a field day with it because it was a fumble. But this should not have been reviewed under the current system. Once the guy ruled the man down, it's over."

George Young, the NFL's senior vice president of football operations and the man overseeing the project, knows the new replay system is not perfect and is fully prepared to have similarly blown plays during the season.

"What people have to realize is that some things are not reviewable," Young said. "They also have to understand that this is not a panacea for eliminating every mistake.

"That play Monday night we discussed at length in the Competition Committee. We had the same kind of call in the Green Bay-San Francisco playoff game last year. The official who made the original call that the Oakland guy was down blew the whistle. That's a safety issue, too. If you allow a late whistle, you're going to get in trouble. And these guys don't have 14 eyes. People at home have the luxury of seeing it in slow motion. These officials don't."

Young said he has heard no major complaints from coaches around the league about how the system has been operating, and "I think it's been pretty good. We're just trying to iron out the kinks. Different things come up every week. It's not going to be a perfect system. We'll try to make it as perfect as possible. But there is no perfect system."

It is an expensive system, with digital equipment installed in every league stadium at a cost of about $117,000 each. In addition to hiring 16 replay assistants, all with previous officiating experience, the replay booth also has a technician to cue up the live play, a video operator to handle the replays and a "communicator" who lets the video crew know what's happening on the field.

Every review of a play is conducted on the sideline by the referee, and he has the final say in all decisions. Coaches are equipped with a buzzer attached to their belts to signal a challenge to the referee. There were some early glitches with buttons that inadvertently went off when a coach bent down, but those have been eliminated.

And if there are technical problems with the primary digital replay technology, there is a backup system using videotape available in the booth.

"Our people have to get used to a whole new system," Young said. "When there's a challenge, the referee has to go in front of the crowd and the TV people and explain exactly what's going on. There are times they have to explain what someone else in the crew saw. We're working with them on how to deal with the live mikes and how to communicate so everyone understands what's happening. The last thing you want is confusion."

Former Redskins general manager Charley Casserly, who fought for years to get replay reinstated, indicated he has heard little grousing, except that more plays should be reviewable. He also predicted not that many plays will be challenged. A year ago, for example, he said the Redskins didn't have a challengeable play until the seventh game of the season. In last Friday's final preseason game, Redskins Coach Norv Turner challenged two calls, one of which was overturned after the review.

"To me, the new technology makes a big difference," Casserly said. "I observed it first hand during our Buffalo game. It was excellent and far superior to the old system. We have to understand that it's in its infancy and there's bound to be a learning process for everyone involved. But I also see no reason it shouldn't be a huge success."

CAPTION: Starting this week, NFL officials will really get into the new replay system.