Though nearly 70, Jack Paar is still a problem child. This is not a complaint; Paar's incorrigibility is his trademark, his hallmark and, for all we know, his birthmark. It doesn't matter that we wouldn't have him any other way; there simply is no other way to have him.

For his second NBC special of the 1980s, "Jack Paar Is Alive and Well!," the ghost of television past is on his best misbehavior. Even when he appalls you, and he will, he holds your interest. The one-hour show airs at 10 tonight on Channel 4.

NBC executives reportedly insisted that Paar do more new studio segments on this special than he did on his first, so in addition to showing freshly unearthed clips from the old "Tonight Show" he hosted (1959-62) and his subsequent prime-time series, Paar hunkers down for chats with guests Debbie Reynolds and Jackie Mason.

Reynolds is as friskily vivacious as ever but can hardly live up to Paar's billing her as "the funniest lady I know" and one possessed of "the keenest ear of anyone I've ever known." Apparently he hasn't known many impressionists, since he finds Reynolds' vocal impersonations to be wildly accurate. They aren't.

She does a particularly dreadful Jimmy Stewart, part of an amusing but too-lengthy story about working with Stewart on "How the West Was Won."

This follows a dissertation by Paar on his preferences in women's undergarments. Debbie lifts her dress to show him her garter belt and he shouts, "Oh my papa!" -- a hilarious ad-lib if one is familiar with the oeuvre of Reynolds' former husband Eddie Fisher.

Paar shows a clip of Reynolds undressing him mischievously behind the "Tonight Show" desk. He claims this incident was "front-page news for several days." In what papers, pray tell? Earlier, he reprises footage that really did make news, when he stomped off the "Tonight Show" because NBC had censored an innocuous joke from the previous night's telecast. After three weeks, he triumphantly returned.

How loonily earth-shaking all this seemed at the time.

Later Paar unreels a routine by Mike Nichols and Elaine May from "The Jack Paar Program," on which they appeared several times. He calls them "the most talented young people I have ever seen," but the sketch chosen is not their best, and has to do with telephone operators like we don't have anymore. It is very long.

Finally the celebrated, the incredible, the preposterous Jackie Mason, whose 1962 appearance with Paar prompted, says Jack, "the biggest explosion of laughter I have ever heard." Unfortunately Paar pulls an excerpt from it that isn't all that excerptable. But the present-day Mason, whose neck has disappeared into his body over the years, makes up for that with priceless observations from his Broadway smash "The World According to Me."

In his opening monologue, Paar tells a true story about being waylaid onto the "Wheel of Fortune" set while in Burbank to attend NBC's 60th-anniversary party last year. Then he brings on "Fortune" host Pat Sajak to validate the story. It used to be Jack said "I kid you not" and we believed him. Could he have taken to heart those immortal words "Trust, but verify"?

The show winds down with Paar, Mason and Reynolds conversing amiably as folks used to do on Paar's pioneering gabfests. Paar's anecdotes are mostly reruns but it's nice to hear something as substantial as an anecdote again. All we get from TV now are sound bites and one-liners.

Paar's two specials have been good enough to make one wonder what a really ambitious producer would have done with him. Paar produced both himself. "Alive and Well" concludes with him saying he doesn't know how to end the show. Well, he should. It is prime time after all.

Though Paar dips generously into his bottomless pit of first-person tales from years gone by (one more go-'round for that toll booth tale and we all shall scream), he seriously underestimates his own quiet charm. His appearance with Johnny Carson on "The Tonight Show" Thursday was breezily delightful. Carson was immaculately gracious and Paar was full of fun.

A mind is a terrible thing to waste, and Paar ought to do two of these specials a year just to stay active, and yet he's indicated this might be his last because they're too much trouble. Imagine Jack Paar, who wallowed in trouble during his heyday, shying away from it now. Has mouth, will talk -- and should. He owes it to television. And he owes it to himself.