Dan Aykroyd, Tom Hanks, Alexandra Paul, Harry Morgan, Christopher Plummer, Dabney Coleman, Elizabeth Ashley. Directed by Tom Mankiewicz. 1987. PG-13. (MCA, stereo, 106 min., $89.95) DRAGNET Jack Webb, Ben Alexander, Richard Boone, Ann Robinson. Directed by Webb. 1954 (MCA, b&w, mono, 88 min., $24.95) By Andrew Sarris Jack Webb's clipped, deadpan style, complete with musical fanfares, has so deeply ingrained itself in our media consciousness as "the 'Dragnet' effect" that Webb's own 1954 silver screen debut as Sgt. Joe Friday -- after a spectacularly successful long run on radio and television -- plays in 1988 as self-parody.

The percussive musical cues, for example, now seem designed to keep the audience on pins and needles through the commercial break. What started out as a "just-the-facts-ma'am" alternative to earlier crime shows, full of hoked-up melodrama, has ended up as addled affectation in search of anticlimactic authenticiy.

Hence, I now find the '54 "Dragnet," done "straight," is in some ways funnier than the '87 Mankiewicz-Aykroyd takeoff. Aykroyd is at his best mimicking Webb and the presumably innocent '50s style of law-and-order that he represented.

The partner of Aykroyd's uptight Joe Friday, nephew of the original, is a younger audience's hip surrogate. Fortunately, Hanks is as adept at comic timing as Aykroyd, and the two bounce wisecracks off each other with '30s fluidity and grace.

Aykroyd and Mankiewicz worked together on the script, and the result on the soundtrack is only slightly warmed-over "Saturday Night Live." The plot is something else again. No idiocy of contemporary kiddie taste is overlooked as stunt drivers and special effects technicians take over whole chunks of a preposterous account of the struggle between Good and Evil in the intentionally grotesque setting of the City of Angels.

Such overqualified talents as Morgan {who played Friday's sidekick in the television series from 1967 to 1970}, Plummer, Coleman and Ashley go through their paces for, one hopes, their fat paychecks. The dreary jokes about male and female virginity are calculated to appeal to the most callow adolescent.

The videocasette renter with subtler tastes might find some marginal compensation in the sheer professionalism of Aykroyd and Hanks -- and a sometimes unexpectedly witty script.