"Run, Don't Walk," ABC's new Afterschool Special today from 4:30 to 5:30 on Channel 7, is a gentle little parable, relatively unbelievable but nonetheless well-intentioned, about a couple of youngsters in wheelchairs.

Eighteen-year-old Samantha Anderson (played by a more-than-18-looking Toni Kalem, but who's counting?) has lost the use of her legs in a horseback-riding accident a year before. As the show opens she is returning to her high school, hoping to keep out of the (school) public eye.

Lo and behold, there is another wheelchaired classmate, one Johnny Jay (played by younger-than-18-looking Scott Baio), wheeling around with a toilet seat around his neck, campaigning to beat the band for wider access to the bathroom stalls.

This young man is an activist. He was, he points out to Sam, born that way (without use of his legs) so he's "not mad about not being able to walk because I never did."

Sam is offended as much as Johnny's high profile as by the ingenuously open scatological bent of his campaign -- even when she is rather too graphically confronted with the problem.

On the other hand, Sam is taking to tooling along in her chair with a jogging teacher and wants nothing more than to enter the marathon . . .

Henry (Fonzie) Winkler is executive producer of "Run, Don't Walk," and, through the adept Baio, he is able to convey some of his vaunted charm.

In fact, Baio is genuinely funny from time to time and the special is often appealing when it is not being just a hair condescending.

Rosemary Prinz and Jim McKrell play Sam's almost-too-understanding parents; Dee Wallace is the jogging teacher.

There's nothing offensive about this special, despite the particular focus of young Johnny's campaign, and it certainly doesn't hurt to be reminded that, as Johnny puts it, "You can't believe how many doors you can't get through in a wheelchair." Nevertheless, it's all a little vague, a little unreal. A near miss.