San Francisco ? It is early on Sunday morning on March 1, the last day of the comic/TV/movie convention called WonderCon. Four of the cast members from NBC’s “Chuck” — Zachary Levi, Yvonne Strahovski, Joshua Gomez and Adam Baldwin — are spending their day at the convention. This is just the latest in a long list of special appearances.

They are trying to drum up viewers with personal appearances around the country.

“This is just part of the job and something we are glad to do because we love this show,” Strahovski, who plays superagent Sarah Walker, says moments before joining castmates in a panel discussion.

She’s willing to make such one-on-one appeals for viewers because everyone in the cast knows network executives have no problem canceling a series that isn’t drawing enough viewers. Just last week, ABC announced the cancellation of the critically heralded “Life on Mars.”

“Chuck” could use some more viewers. “Chuck” also doesn’t have the critics buzzing. The show isn’t held in the same high regard as a “Heroes” or “Lost.” But it certainly has all of the elements that should be attracting viewers.

Levi plays Chuck, a reluctant government secret weapon who has had tons of secret information downloaded into his brain. He’s part-goof, part-hero. Baldwin brings a tongue-in-cheek bravado as one of the government agents assigned to watch Chuck.

And Strahovski is the sexiest government agent since Emma Peel from the 1960s show “The Avengers.” Make that Sydney Bristow from “Alias” for those of you under 50. This is a show that blends comedy, action and romance.

Making sure the public is at least aware of what the show has to offer is as important to the cast as wardrobe and scripts.

“If people will just give us a chance, I think we will get them hooked,” Levi says.

Gomez adds that what makes the group so passionate about trying to pull in viewers is doing a job they love.

“To do an appearance like this is an honor,” Gomez says.

One of the messages executive producer Chris Fedak planned to get across to those at the convention is the remaining episodes of “Chuck” to air this year will be filled with twists and turns. Series creator Josh Schwartz says these episodes will take the series to the point they have wanted to be since the show launched September 2007. He’s not saying what exactly that means.

It better mean enough viewers watch to convince NBC to keep “Chuck.” Last week, “Chuck” attracted 6.6 million viewers to rank 43rd among all 112 network shows. Because NBC’s lineup is so weak this year, “Chuck” was the seventh-highest-rated show on the network.

The good news for “Chuck” is that NBC has not been able to launch a hit TV show in years. All the cast and crew can do is try to build enough viewership to keep the bubble from popping — even if they have to do it one conventioneer at a time.