By JERRY BUCK AP Television Writer                              
                LOS ANGELES (AP) - John Mantley, who has a reputation
                  as a doctor of sick TV shows, has been attending to an anemic ''Buck Rogers''
                  this year.                              
                The patient has shown signs of improvement, but
                  the likelihood of a full recovery seems remote.                              
                ''What I'm putting on the air today is a far cry
                  from what I ought to be doing,' said Mantley. ''The holes in some scripts
                  are embarrassing, but we don't have time to correct them.''                              
                Mantley, who previously produced ''Wild Wild West,''
                  ''Gunsmoke'' and ''How the West Was Won,'' took over the NBC series after
                  it had limped along for two years.                              
                ''This is absolutely the most difficult project
                  I've ever done,'' he said. ''You've got to create a new world every week.
                  You've got a new wardrobe, new location and all kinds of effects. We have
                  enormous wardrobe problems, enormous set problems, enormous makeup problems,
                  enormous budget problems.                              
                ''You spend so much time on the effects you don't
                  have time for the human stories. Without the actors' strike, which gave
                  us time to prepare, this show would have self-destructed in a few weeks.''                              
                In the Thursday night series, Gil Gerard stars
                  as Buck Rogers, a present-day astronaut who is frozen while on a space
                  mission and wakes up in the 25th century. Erin Gray stars as Wilma Deering.
                  The series is adapted from the comic strip created in 1929 by Dick Calkins
                  and Phil Nowlan.                              
                Mantley said he agreed to take over the show for
                  several reasons. For one, he owed favors to people, not the least of whom
                  was Fred Silverman, president of NBC. ''Fred said it has potential, and
                  maybe you can fix it,'' he said. ''I owed a lot to Fred.''                              
                Another reason, he said, ''I've always loved science
                  fiction. My first book, 'The 27th Day,' was science fiction and was made
                  into a movie. I wrote science fiction for the pulps, and I own the rights
                  to Isaac Asimov's 'I, Robot' and 'The Rest of the Robots.'                              
                ''And the third reason,'' Mantley said, ''is that
                  the remuneration was extraordinary.''                              
                He wouldn't mention a figure, but reports in the
                  industry indicate his salary is not merely extraordinary - it is astronomical.
                  Few television stars make as much. The reason he was able to command such
                  a salary was that Universal was anxious to recover its enormous investment
                  in the show. If Mantley could just keep ''Buck Rogers'' going a few more
                  years, the syndication and merchandising value of the series would increase
                  greatly.                              
                After looking at only a few shows, Mantley said
                  he knew he had to drastically revamp the show. ''For my taste, I thought
                  the shows were empty,'' he said, ''but I don't think I've done a hell of
                  a lot better.                              
                ''The first thing I did was get them away from
                  Earth. I felt it as a restrictive atmosphere, and so did the network. I
                  came up with the concept of the Searcher, a spaceship looking for the 'lost
                  tribes of Earth.' In every great civilization there have been migrations,
                  from the Puritans to the boat people. It seemed to be to be logical that
                  after the atomic war people would have left Earth.''                              
                He also set out to give Buck Rogers more dimension
                  as a character. ''I wanted to stretch Gil Gerard as I did James Arness
                  on 'Gunsmoke,' '' he said.                              
                Some of the changes caused controversy. Some viewers
                  had complained that the voice of Twiki the robot was too cute. But even
                  more viewers demanded the return of Mel Blanc as the voice. ''So we brought
                  Mel back and got still more letters,'' Mantley said.                              
                One characteristic of science fiction fans is
                  that they are not reluctant to take pen in hand to express a thought about
                  a show.                              
                ''It seems astounding,'' said Mantley. ''A thousand
                  years ago when I did 'Wild Wild West' I never got letters telling me how
                  to do the show. Now we get some very intelligent letters that go into great
                  detail. And some are violently opposed to the changes. In 11 years of 'Gunsmoke'
                  I don't think I got more than a handful of letters expressing anger over
                  a show. But science fiction has very, very devoted fans.''