NBC appears to have snatched banality from the jaws of originality with "Remington Steele," the new semi-serious detective series from MTM premiering tonight at 10 on Channel 4. A pilot episode of the show, screened earlier this summer, featured an intelligent, competent woman continually coming to the aid of a handsome but bumblingly incompetent man in the detective agency she ran.

Things changed somewhere along the line. The woman became weaker, the man more dominant. In tonight's premiere, a completely different episode from the pilot, the woman at one point sees a corpse in a closet and runs squealing for help into the big strong arms of the man. A show that had novelty, sex appeal and a healthy revisionism going for it now appears wearily standard and stale. NBC sent back the sparkling Dom Perignon and ordered up a flat mug of Blatz.

The lesson for producers would seem to be that networks believe viewers will tolerate only limited upsetting of the sexual stereotype applecart. But Michael Gleason, the executive producer of the series, and the writer of tonight's introductory show, said yesterday from Hollywood that "the direction of the show has not changed" and that "I don't think the flavor of the show has changed," either.

In the original pilot, ace detective Laura Holt (played by ace comedic actress Stephanie Zimbalist) set up an agency but starved for clients because people wouldn't accept a woman as a private eye. So she invented a fictitious agency chief named Remington Steele; no one would ever see him, but if they thought a man ran things, they'd use the agency. Then, surprise, a promiscuous playboy who really was named Remington Steele (Pierce Brosnan, who could make it as a young James Bond) showed up. Rather than risk exposure, Holt signed Steele up as the titular head of the agency, a kind of human logo.

Remington was able without effort to wow almost any susceptible female, a quality Holt despised but to which she found herself not entirely immune. Her resistance threatened to crumble at any moment and this gave the situation a cute sexual tension. (An altered version of this episode will be shown next week, Gleason said.)

As revised, Brosnan plays a freelance secret agent named Ben Pearson who sort of stumbles into Steele's identity. The program tonight is not nearly so witty, or saucy, as the previous version. It wastes time on a boringly circuitous plot about stolen gems and bothers little with character detail. Also, "Pearson" says he's working for the government of South Africa; is that supposed to make him more lovable?

Gleason said yesterday that the playboy's philandering -- a prominent feature of the first pilot -- was toned down because "the question people asked, at the network and elsewhere, was, why does she keep this guy around? Now we show that in his particular area of expertise, he operates quite well. He sees the detective thing as an amusing adventure and keeps stumbling and bumbling about."

Asked if there had been a conscious effort to alter the original balance of power -- strong woman, weak man -- because of network pressure, Gleason said, "No, no, not at all." Maybe Laura Holt still is a strong woman. But "Remington Steele" is now a very weak show.