LBJ used to come before us with a heavy heart. Fred Gwynne comes before us with a heavy face. His long, saggy, charismatically weathered visage has served him well in works as disparate as the "Munsters" TV series and Francis Coppola's film "The Cotton Club," in which Gwynne and Bob Hoskins shared rosy comic highlights.

Unfortunately, Gwynne and his estimable countenance are only wasted on "Jake's M.O.," an unsold series pilot that airs tonight as a one-hour drama special on NBC, at 10 on Channel 4. Gwynne's charm is in its usual ascendant state, but the vehicle, a lumpily formulaic crime caper by writer and executive producer Lane Slate, belly-flops on takeoff.

Gwynne plays lovably crusty Jake Tekulve, whose 40 years as a police reporter have made him an unofficial member of the Los Angeles police force, even if his sleuthing on behalf of the ragtag County News Service gets on cops' nerves. The character is based on a real reporter who helped solve the Hillside Strangler slayings.

As directed by Harry Winer, who hasn't discovered the close-up yet, Jake ambles about much too slowly and cautiously, trying one's patience as he does. Long scenes in which he figures out a serial killer's method are boring, and Jake's badinage with the cops is strained, although James Avery as detective Abel Barnes gives that character some dramatic weight.

Not content with mediocrity, Slate opts for offensiveness. The news service, we are told, is owned by a frivolous widow known around the office as "the bimbo." The role is played as a disgrace to her sex by Claudette Nevins. She takes Jake to lunch, and Slate's dialogue includes smutty double-entendre incorporating the term "sucks."

How low do we have to sink in prime time? The networks see their mission as providing depressing new answers to that question.

Slate has one bright moment in the dialogue department: A cop begins sarcastically paraphrasing a very tiresome and overplayed GE commercial ("They come from near and far, with names like ..."). GE, which now owns NBC, only has about four commercials on the air and the company likes to show them over and over and over. They beat good things to death.

Another of Slate's handful of nifties is delivered by Avery, who says, "I haven't had an original thought in 20 years, which is why I am perfect for this job." Say, he sounds like a network executive! But network executives can't be all bad, because at least some of them had the sense not to buy "Jake's M.O."