text: Just when you thought it was safe to let your kids turn on the TV or go into the toy stores . . . the Mighty Morphin Power Rangers come back with a vengeance.
  
  Is there anyone with kids between 3 and 12 who hasn’t heard “Go go Power Rangers” sung around the house? Or who hasn’t been talked into buying at least one of the action figures depicting the teenage band of good guys and gals who find power in strange places and use it to save the world from villains like Rita Repulsa?
  
  Season No. 4 for the series, which runs weekdays and on Saturday mornings, officially begins today. And there is much anew about everything: The name becomes “Power Rangers Zeo”; a new source of power is unleashed, that of the Zeo Crystal; a new fleet of Zords--the vehicles commanded by the Rangers--will be introduced; new uniform and color assignments will be given; and more villains and monsters will arise.
  
  Even upcoming “Power Rangers” computer software will include the Zeo name.
  
  
  To some, this may appear to be an act of high-tech anxiety. After all, the action figures now sit idle on many a toy shelf and the first full-length “Power Rangers” movie was a disappointment at the box office last summer. But those behind the still high-rated series insist it’s just an attempt to give its increasingly sophisticated viewers more.
  
  “The ratings game is part of our life and, while we’re still at the top, there are lots of people chomping at our heels,” explains Peter Dang, president of the Children’s Entertainment Group of Saban Entertainment, which produces the series for Fox. “Most people wait to change when they’re going down, but we thought it would be easier to do when we’re No. 1.”
  
  The challenge was to make heavy-duty adjustments, yet not turn off millions of loyal little viewers.
  
  “We’ve worked hard to keep the equity of what ‘Power Rangers’ is and yet reinvent itself,” Dang says. “At one point we considered killing everyone off but felt that would be too traumatic. Now some of the Rangers remain, some of the villains, and Bulk and Skull are back. Basically, this show is a soap opera for kids and you can’t change everything on them.”
  
  
  The Power Rangers themselves feel excited. “In the past, people have associated us mostly with our helmets,” explains Catherine Sutherland, who came in last season as the Pink Ranger. “But now we’re going to be allowed to establish our identities more.”
  
  The women on the series have never been mere accessories, and Sutherland says that’s truer than ever in “Zeo.” “The last Pink Ranger [Kimberly] was sort of cutesy. My character is more mature, very strong, but not afraid of being feminine.”
  
  As Saban and Fox see it, the expectations for the “Power Rangers” have become unreasonably high. Dang describes this as the “post-phenomenon” era, and the question is: Can such a blockbuster be allowed to morph into a mere hit?
  
  “We’re no longer a phenomenon,” he admits, “we’re just No. 1. If we sell 1 million toys, people say, ‘Just a million?’ When you’re up against that mentality, you have to do something radical.”
  
  
  Radical in this case entails not just the changes in the series itself, but the very idea of launching it midseason, as it were, rather than in the fall. Also, a multitiered push is being made on both the television and merchandising fronts.
  
  “We decided we had to be singular of purpose and do it when the absolute focus was on us,” says Dang, looking downright Churchillian before his “battle plan,” a chart showing how all divisions were leading up to D-Day. These include heavy promotion on television and a repeat of the 10 episodes that concluded with the Rangers being stripped of all their powers. That cliffhanger folds neatly into today’s premiere.
  
  And of course there is the stuff. The toy store near you may soon feature every size Zeo Power Ranger, including the Pink Zeo Ranger (with shield-spinning action), the Yellow Zeo Ranger (swinging a club in each hand) et al, plus a new batch of Zeo Power Zords, Micro Zeo-Zord Playsets and, of course, the Zeonizer, a new morphing mechanism.
  
  But while those behind the show ooze vigor, the word from the street is either boredom or, at best, caution.
  
  
  “For us, the Power Rangers are completely dead,” says Caroline Seymour from the popular Star Toys in Brentwood. “I don’t get a call a week for one.”
  
  At Puzzle Zoo in Santa Monica, families used to line up around the block when a new shipment of Power Ranger toys came in. But even there, things have changed.
  
  “I have no qualms about ordering some of the new line,” owner Alan Saffron says, “but where I once ordered in the tens of thousands, and sold them within hours, now I’m ordering 50 to 100 and I’ll be happy if I sell them in a month. I can’t sell the old Power Ranger stuff with a 20%-30% discount. The new Zeo toys are good quality, but I’m afraid the Power Rangers may be going the way of the Ninja Turtles.”
  
  * “Power Rangers Zeo” premieres at 8 a.m. today and also will air Monday through Thursday at 5 p.m. on Fox (Channel 11).