NBC’s Grim Task: Revive the Magic : Television: From news to entertainment, the former hit-happy network needs revamping. And the threat is greater due to new competition.

If ever a television network needed to pull itself together--from news to entertainment--it is NBC.

All of the Big Three networks have been in trouble before but only in times when the overall business was more robust and failure did not seem as ominous because of formidable new competition and technologies.

It seems incredible that the awesomely successful NBC of just a few years ago, led by “The Cosby Show,” should be in such trouble. But, if there is any hope at all, it is that there is no way to go but up, barring another unexpected haymaker.

NBC at least will have the fresh input of new faces running both the news and entertainment departments.

Michael Gartner, president of the news division, resigned under pressure this week in the wake of a faked truck-crash story on the “Dateline NBC” news magazine. And entertainment programming recently was turned over to Don Ohlmeyer as NBC’s West Coast president.

But the tasks for both Ohlmeyer and the new head of NBC News, yet to be named, are challenging in the extreme.

NBC News has the tougher job because the truck-crash story tarnished the public image of the network and, in fact, of television journalism--illuminating the mad race for ratings among the many prime-time reality shows that incorporate entertainment-style elements as they become major profit centers.

The network not only apologized for the rigged “Dateline NBC” story but also, shortly afterward, for broadcasting misleading footage on the “NBC Nightly News” about the environmental effects of logging. An NBC investigation of the fake crash segment is under way.

But with the increasing number of news and reality shows trying to emulate the success of “60 Minutes”--and competing with entertainment in prime time--it would seem Pollyannaish to believe that other gaffes will not occur, especially since the networks have lost many experienced journalists in staff cutbacks.

Ohlmeyer says of the pressure on NBC News: “They’re going to be under a microscope for God knows how long.”

Acknowledging the impact on the network’s entertainment programming as the two divisions pull together to try to revive NBC, Ohlmeyer adds: “Advertising and promotion report to me. We can use those things to reinforce the good things that (NBC News) has done.”

It will take a good deal of resuscitation. One sharp critic is former NBC News president Lawrence Grossman, who targets the news division’s prime-time series “I Witness Video,” saying it is “an entertainment show” and adding: “I’d like to know what editorial checks they have on those things.”

In daytime, meanwhile, an NBC series that features newswoman Faith Daniels and will leave the air on March 19 has scheduled such recent and future subjects as: “Raped and Pregnant,” “Man With Two Wives,” “Families of Murderers,” “Freeze Me So I Can Live Again,” “People Who Have Met Angels,” “My Wife Loves ‘Soaps’ More Than Me,” “I Married a Con Man” and “Sued Over My Implants and Won.”

While NBC News tries to overcome a succession of missteps in recent years--from forcing Jane Pauley off “Today” to botching its coverage of the 1989 Northern California earthquake--it is probably impossible, in the era of cost-effective reality shows, to restore the distinction of earlier years. And CBS and ABC are not much better off when it comes to going along with the contemporary trend. Ohlmeyer’s entertainment task has more to do with good old-fashioned network competition, as opposed to messy matters of fakery and credibility.

With CBS the solid leader and ABC second, Ohlmeyer and his staff have begun taking initial steps to get the network up and running again. Without doubt, the single most promising night of NBC entertainment programming before summer is shaping up to be the finale of “Cheers” after 11 seasons as a TV classic.

According to Ohlmeyer, “The last five episodes of ‘Cheers’ lead up to the finale,” which airs May 20 as part of a special evening. The night starts with a one-hour episode of “Seinfeld,” followed by an hour retrospective of “Cheers” and then the one-hour finale of “Cheers.”

In addition, says NBC, if enough cast members of “Cheers” are available, “The Tonight Show” with Jay Leno will originate the same night in Boston from the Bull & Finch tavern, with which the departing sitcom has long been identified. An NBC spokeswoman says, “It’s moving ahead and looking hopeful.”

At the moment, NBC doesn’t have much clout in its regular prime-time lineup. Of the 25 top shows in the national ratings released this week, NBC had only five--the successful Monday tandem of “The Fresh Prince of Bel-Air” and “Blossom,” plus three Thursday entries: “Cheers,” “Seinfeld” and “Wings.”

In short, the light at the end of the tunnel is still way out of sight for NBC. Four lighthearted mystery movies with Bill Cosby next season, with an hour series spinoff in 1994, are in the works. But the weekly fall schedule that NBC announces this spring will give a fuller notion of whether it really is on the way back.

“L.A. Law” returns April 1 in a last-gasp attempt to win back its lost audience. An on-air plea last week promised: “This will be the ‘L.A. Law’ you remember. Case closed.”

Johnny Carson has agreed to come back for some NBC shows, and Ohlmeyer is planning on “getting together” with the comedian for “whatever he would like to do.” And Ohlmeyer’s entertainment chief, Warren Littlefield, told the cast of “Mad About You” at a season-end wrap party Wednesday night that the series will be back next season.

“I’ll Fly Away,” however, is still an expected cancellation. Ohlmeyer says that the show is “great” and that he’s looking for a financial solution to the ongoing loss but that “we can’t continue to lose the kind of money we’ve lost on it.” PBS has inquired about picking up new episodes of the show--if it can afford it--should NBC drop the series.

The way things are now, NBC’s most lively daily programming is on its talk-and-business cable network, CNBC, which devotes itself next week to phone calls from viewers. The interactive format features a Monday “Talk Back America” special at 9 p.m. with a number of its hosts on one show: John McLaughlin, Tom Snyder, Dick Cavett, Phil Donahue, Vladimir Pozner and Bob Berkowitz.

While NBC is struggling, CNBC broke into the black last year. But, says Ohlmeyer, “NBC plans to be around.” He says that his marching orders from network president Robert Wright were: “Get out of third place.”