Coach Ted Marchibroda was practicing positive thinking on himself yesterday as Lydell Mitchell extended his holdout through the 11th day at $500 a day.

The whole training camp at the Goucher College campus was abuzz with the topic as the Colts prepared to take on the Pittsburgh Steelers on Saturday evening in Memorial Stadium.

It was two years ago that owner Bob Irsay was so distressed about the loss of an exhibition game that Marchibroda was ready to quit in a power struggle with former General Manager Joe Thomas.

Now, Marchibroda is going ahead with the business at hand as if Mitchell had not average more than 1,000 yards rushing the last three seasons and average 64 receptions the last three years. "There is nothing we can do," he said.

Mitchell reportedly turned down an offer of $170,000 in a meeting with Irsay on Tuesday, a raise of $76,000 over his 1977 salary. He is said to be asking for a graduated salary similar to one given by the Steelers to running back Franco Harris.

Harris is represented by the same agent. Lee Goldberg of Pittsburgh. Harris is said to be earning $175,000 this season, with an escalation to $250,000 by 1980.

Goldberg said on the telephone from Pittsburgh. "Lydell is not asking an outrageous figure. Why isn't Lydell as valuable as Franco Harris, or even O.J. Simpson?

"How do you determine a player's value? You do it the same way you compare anything else, be it diamonds or running backs."

Goldberg said that although the negotiations are at a delicate stage, "We haven't reached a critical crossroads in time. I am not averse to making the first move. I'd be in Timbuktu if the Colts want to talk. There is no real breakdown."

Asked if the two sides were far apart. Goldberg said, "You are always far apart until you have the other side's signature on a contract."

The agent said, "The thought has crossed my mind about considering the Canadian Football League, but I have not talked to anyone there.

I'm not sure Lydell wants to move on to another town. He has a business interest ("The Point After" bar and lounge) in Baltimore and other interests on the East Coast (a partnership with Franco Harris in a "Wendy" fast food franchises in New Jersey).

"Baltimore is the only team he has known as a pro. He'd like to see the Colts make it to the Super Bowl. There is no question about his loyalty to the Colts.

"They big question is whether egos will result in bitterness which would make him want to get away, even take a loss to do it.

"The new collective bargaining agreement doesn't provide him many options."

There has been an unconfirmed report that Mitchell will sit out this option year on his contract if the Colts do not improve their offer.

If he does, a new club would have to give the Colts two No. 1 draft choices in 1979, and might not want to do that on top of paying Mitchell what his is asking.

A management source said that although Mitchell and his agent walked out once on Irsay in the negotiations on Tuesday, they got together again and parted amicably. "They were closer at that point," the source said.

Marchibroda said that if Mitchell did sit out the season. "It naturally would hurt. He's been a big part of the Colts for the last three years. But as I said, we can't do anything about it. You have to be happy with what you have.

"You just can't think of one player: you have 45 to think of. We did without Roger Carr (wide receiver) and John Dutton (defensive end) when they held out for part of last year. It would be different if we hadn't made a bona fide offer to Lydell to try to get him here in camp."