With Jamaal Jackson on the shelf with a knee injury, the inexperienced Nick Cole has taken over at center and struggled with the snap and other parts of the job.

After practice on Monday, Cole, 26, was asked if the 30-year-old Jackson helps with some pointers.

"I don't want to talk about that," Cole said.

Does Jackson help you out in any way?

"Nah."

Is it because he's trying to keep the secrets of the trade to himself?

"We don't really talk about it," said Cole, who added that he wants to make coach Andy Reid's choice of a starter "a harder decision" when Jackson returns.

Jackson, through a team spokesman, was asked if he helps instruct his backup.

"Me and the other centers talk all the time in meetings and on the field during practice and have a great relationship," Jackson responded.

There is no date for when Jackson can start practicing, but Reid has said that the center, who is rehabbing with the training staff, is unlikely to return by the season opener.

So that leaves the job for Cole - for now.

On Monday, Cole's shotgun snaps went low, high and one time led to a fumble. In the afternoon, he and quarterback Kevin Kolb worked overtime on the exchange.

"There's so many things being thrown at Nick right now," Kolb said. "He's got a lot of stuff going through his mind and sometimes more than we normally have."

And that is just one of the line's issues.

The foot injury that has sidelined starting left guard Todd Herremans has been deemed a minor by Reid. But Herremans has yet to practice with the team since minicamp in early May.

The line suffered another casualty Monday when starting right guard Stacy Andrews missed the afternoon session with an unspecified shoulder injury.

That's three regular interior line starters out of action. But Reid was not alarmed.

"I'm good with the [backups] we have," Reid said. "Whoever is there we're good with. We're lucky to have depth there."

With the starting center, left guard and right guard sidelined, Max Jean-Gilles and Mike McGlynn have filled in for Herremans and Andrews, respectively, and Cole has taken over for Jackson. So Eagles general manager Howie Roseman was asked if the injuries made an acquisition necessary.

"We like the guys we have," Roseman said. "But like at any other position, if we find something that we think helps out football team then we'll do it. But I like the guys we have."

The Eagles didn't add a single offensive lineman in the off-season, and Roseman pointed out that the team has three younger lineman - tackle King Dunlap, guard Fenuki Tupou and McGlynn - they have developed and believe are ready to contribute.

Cole started the first 14 games of last season at guard primarily in place of Andrews, who they signed even though he had knee surgery in November 2008.

Andrews, however, never quite made it back from surgery, and ended up inactive on game days. He's still trying to get caught up.

"I know I still have things to work on," Andrews said. "But it'll come."

Said Reid: "He's working through it, learning, and doing well, I think."

The Eagles' tackles - Jason Peters and Winston Justice - haven't caused as much concern, although Justice was whistled for back-to-back false starts Monday. Reid pulled the right tackle for a snap and inserted Dunlap.

The Eagles said McGlynn, another of the young linemen, would compete at center because Cole is so versatile at guard. But the third-year Pittsburgh product has yet to take a snap with the first team.

"I still consider it a full competition," McGlynn said.

Contact staff writer Jeff McLane at 215-854-4745 or jmclane@phillynews.com. Follow him on Twitter at www.twitter.com/Jeff_McLane.