Johnny Carsonroutinely turned missteps to his advantage with uncommon grace and skill, becoming an enduring icon of late-night TV on NBC’s “The Tonight Show” partly because of whatDennis Millerhas described as a “Houdini-like ability to extricate (himself) from the bad joke.”Carson’s gone, but they’re still making mistakes at NBC, especially around “Tonight,” and only making a bad joke worse.First in trying to keepConan O’Brienfrom leaving, then in trying to keepJay Lenofrom leaving and now in trying to keep affiliates burned by those first two moves from open rebellion, Carson’s old network has found it can’t wriggle out of its straitjacket. Forget about the shackles, the locked trunk and swimming to the surface.”The Tonight Show” is a television institution of more than 55 years. Yet the people running NBC Universal are battering it rather than burnishing it. It’s emblematic of how, even before the cable guys take over, they’re allowing their once-proud, once-dominant network to wither and fray.And with its inability to take quick, decisive action regarding two men who have generated hundreds of millions of dollars in revenue for it over the last decade and a half, NBC Universal is treating Leno and O’Brien with no more dignity than the attention-hungry White House gate-crashers hoping to stay on Bravo’s “The Real Housewives of D.C.”That said, if NBC can’t talk Leno and O’Brien into going along with some kind of face-saving compromise, the already costly mistakes of moving Leno to prime time to accommodate O’Brien’s move to “Tonight” will cost the company millions more in contractual penalties.It’s about this point when Carson would do a humble little soft shoe asDoc Severinsenand the band played a few bars of “Tea for Two.”Where did everything start to unravel? One could argue it was when Leno was named overDavid Lettermanto host “Tonight” after Carson left in 1992. That’s because Letterman’s defection enabled CBS to establish a viable late-night franchise while Leno learned the job.But the latest sequence of staggers and stumbles started when Leno was cruising along at No. 1 in late-night in 2004. NBC was fearful it would lose O’Brien and promised him Leno’s “Tonight” job in 2009.Leno only got stronger in the intervening five years, however, meaning NBC was at risk of putting the top-rated late-night host on the open market. Dumb.Staving off a move by Leno to ABC, NBC blew up its prime-time schedule and gave Leno a nightly show. It was cheaper, so it wouldn’t have to have high ratings to do all right for the network economically, the execs said. At worst, they figured if Leno bombed, rival networks wouldn’t want him.They should have seen the move would undercut O’Brien. And they refused to listen when affiliates correctly anticipated the lower ratings for Leno in the last hour of prime time would cost them dearly by dragging down their late local news ratings.One thing that has changed is NBC has realized its affiliates may be getting compensation from cable and satellite carriers and it would like a share of that cash, so it has to make nice with the stations.Now Leno is moving back to 11:35 p.m. What will still, for legal purposes, be called “The Tonight Show” with O’Brien will go to 12:05 a.m.If O’Brien balks, Leno just retakes “Tonight” with O’Brien eventually landing elsewhere.And the Environmental Protection Agency will declare NBC’s 10 p.m. hour a toxic cleanup site, and the network will see if anything new can sustain itself there.When a punchline-gone-wrong was met with groans, Carson would return volley with a deft zinger.Perhaps the longest sustained laugh in the storied history of “The Tonight Show” came because Carson instinctively salvaged a mistake. Embarrassed by an errant tomahawk throw, actorEd Amesmoved to retrieve the ax lodged in the groin of his outlined target. Immediately recognizing the visual gag of the gaffe, Carson yanked him back to milk the moment. Instant classic.You’re unlikely to see anything like that these days at NBC, and not just because the network’s leaders only seem to know how to compound their mistakes.Given their recent track record, who’s going to let any of these people anywhere near a sharp object?

• Phil Rosenthal