Dean Stockwell, left, as Admiral Al Calavicci and Scott Bakula as Dr. Sam Beckett in “Quantum Leap.” (NBC/Getty Images)

As a kid, I couldn’t get enough “Quantum Leap.” I never watched new episodes because television was a rare treat during the school year, but on summer vacation — with no oversight from my working parents — I watched it every day. Reruns aired around lunchtime on some cable channel or another; USA, maybe? The details are as hazy as those humid D.C. afternoons, yet I can almost tap into the buzzy excitement I felt before spending an hour with the a-dork-able Dr. Sam Beckett.

Sam, played by Scott Bakula, was an earnest everyman, not to mention a brilliant physicist, and he was trapped in a time-travel loop. Each episode, he teleported to a different era and inhabited a stranger’s body to alter history for the better. All the while, he kept hoping the next leap would bring him home.

I wasn’t a science fiction fan, but the show won me over anyway. Every adventure was so singular, and the series was remarkably progressive. Sam became a leggy blonde in the 1960s dealing with sexual harassment and a black man fighting discrimination in 1955, but also an unenthusiastic Ku Klux Klan member from Alabama. At one point he landed in the body of Lee Harvey Oswald.

He was literally walking in other people’s shoes, experiencing their predicaments, privileges and indignities. If any television series helped me become more compassionate, this was the one. Then again, who am I kidding? I also just really adored Sam’s witty sidekick, a hologram named Al (Dean Stockwell), who had a naughty sense of humor and a twinkle in his eye. No one could see him but Sam, so he sometimes liked to joke about secretly watching women change clothes — a habit that might not get the same laughs today.

The show ran from 1989 until 1993, and I doubt I watched it once I became a teenager. By then, must-see TV was required viewing, and, like a lot of high school girls, I fell under the spell of dramas fueled by angst, like “My So-Called Life” and “Party of Five.”

In “Grease,” Sally Olsson (Olivia Newton John) changes her look to be with Danny Zuko (John Travolta). (Paramount Pictures)

It was another 15 years before I thought about “Quantum Leap” again. I had recently moved to the West Coast, where all the chill vibes, hiking trails and fresh avocados weren’t enough to lighten the debilitating weight of homesickness. My entire family, including one precious baby niece, were thousands of miles away. To ease my pain, my sister flew out to visit me one weekend and, during a late night after too many glasses of wine, we stumbled across an old episode of “Quantum Leap” while flipping through the channels.

It felt like kismet. Here I was, watching a show about time travel that could transport me to another, happier era. For one hour, I could leap home.

But there was a malfunction.

The show in front of me wasn’t as brilliant as the one in my memory — and it wasn’t just because of Al’s peeping Tom jokes. To be fair, the episode about a trapeze artist in a traveling circus wasn’t a series standout. Still, everything looked so dated. In the year “Iron Man” came out, of course the special effects on a show from 1990 were going to seem shoddy. But the acting, too, was campier than I recalled, the story duller. The voice-over narration was overbearingly superfluous and the opening credits sounded like a synthesizer-filled parody.

We lasted about 10 minutes, then decided to watch “Flight of the Conchords” instead.

I haven’t watched “Quantum Leap” since, but I’ve thought about it a lot. What had changed? Was it just my sad mind-set that night? The show was nominated for Emmys, and the leads won Golden Globes for their performances, so it couldn’t have been that bad. Now that it’s streaming on Netflix, I could give it another shot, but I’m afraid of what will become of those carefree summer memories. Because time and again, I revisit a show or a movie only to feel profoundly disappointed.

Goldie Hawn as Gloria Mundy and Chevy Chase as Tony Carlson in the 1978 action-comedy "Foul Play." (Paramount Pictures)

The reasons aren’t always the same. “Sixteen Candles” was a laugh riot when I was 12, but watching it recently, I couldn’t overcome the racist caricature of Long Duk Dong. The most romantic movies of my childhood revealed themselves to be shams, years later, when I realized the male leads were selfish jerks who didn’t deserve the girl. (Looking at you, “Reality Bites.”) “Nightmare on Elm Street” gave me actual nightmares; now it all looks laughably fake. And I regretted encouraging my niece (who’s no longer a baby) to watch “Grease” last summer as it dawned on me that the slumber party mainstay had an extremely dubious message: If he doesn’t like you the way you are, try wearing tighter pants.

Then again, even as our culture has changed, some dated movies beyond the celebrated classics still thrill me. I’ve watched “Tootsie” more times than I can count, and my fond feelings for the movie only get deeper. A little action comedy called “Foul Play” was my favorite movie as a girl, although now I’m more charmed by the chemistry between Goldie Hawn and Chevy Chase. And, while the clothes and music are so very ’80s, “Baby Boom” still has a remarkably timely message about being a working mother that I couldn’t have begun to understand when I first saw it decades ago.

Is it better to leave the shows and movies we once loved in the past? Maybe. But sometimes even the disappointment is worth it in a way. Sometimes, when things don’t hold up, we learn lessons about our societies, our sensibilities and ourselves.

One late night in Northern California, “Quantum Leap” let me down. I realized then that a show couldn’t transport me back home after all. But then I figured out I didn’t need it to. I could transport myself — for good.