The Los Angeles Lakers had their running game working again tonight, and the Philadelphia 76ers couldn't keep up. In fact, they didn't even come close.

Led by Norm Nixon's 29 points and a devouring defense, the Lakers took an early lead and hardly ever let up. The 129-108 victory at the Forum gave Los Angeles a 2-1 lead in the best-of-seven NBA championship series. Game 4 will be here Thursday night (WDVM-TV-9 at 9 p.m. EST).

Nixon seems to be the catalyst for the Lakers. As they swept a record nine straight games in the playoffs, he led the team with a 22-point average. When the Lakers lost their first game in 46 days on Sunday, he scored six points. Tonight, as the Lakers improved their playoff record to 10-1, he also had six assists and three steals.

"I think if I don't have a good night scoring, I hurt the team," Nixon said after making eight of 10 shots in the second half. "So I went out from the gun and tried to score."

Said Maurice Cheeks, the 76ers' guard who tried to guard him: "There really was no difference in his intensity between Sunday and tonight. He just got his shots going, and once they started falling there was no way to stop him. I tried to deny him the ball, but that's a tough thing to do because he handles it so much."

The Lakers dominated so totally that it hardly mattered when center Kareem Abdul-Jabbar went to the bench late in the first quarter with three personal fouls and didn't play the final 14 minutes of the half.

After Philadelphia shot 24 percent in the first quarter, the Lakers had a 12-point lead. They maintained it at halftime and increased it to 23 points in the first 3 1/2 minutes of the second half.

Even though the 76ers got 36 points from Andrew Toney and 21 from Julius Erving, this was no contest after the first eight miunutes. In the last 14 championship series, the team that won Game 3 won the title 12 times. The Lakers seemed quite aware of that statistic tonight.

"We didn't play well except in some isolated spurts in the two games (mainly a 40-9 streak in 10 minutes of Game 1) in Philadelphia," Lakers Coach Pat Riley said. "But tonight we put a whole game together."

Said Billy Cunningham, the 76ers coach: "I just thought they (the Lakers) were a step quicker than we were in every respect. They played great basketball and got the ball to the right people. I know it's simplifying things, but we just didn't play well and they did. But we'll be back Thursday. We've been in this position many times before in the playoffs and always come back. We'll come back again."

The 76ers won Game 2 at the Spectrum Sunday because, besides the fact Nixon was three for 14, they negated the Lakers' trapping defense and outrebounded them in the 110-94 victory that evened the series.

The traps caused havoc for the Sixers tonight and the Lakers outrebounded them, 48-43.

"Our big guys said before the game that they were going to hit the boards hard and they went out and did it," said Nixon.

Riley made one adjustment with his match ups to try and get more rebounds: he put his best rebounder, Magic Johnson, on Julius Erving to get him closer to the basket, and Erving, who dominated Sunday's game with 24 points and 14 rebounds, was outscored and outrebounded by Johnson tonight. Erving finished with 21 points, but had only three rebounds and three assists, while Johnson scored 22 points and had nine rebounds and eight assists.

With Johnson inside, that left Nixon outside to lead the break. He scored 12 of his points in the third quarter when the Lakers clinched the victory and his back-to-back 18-footers midway through the quarter gave Los Angeles a 25-point lead, its biggest of the game.

"Magic has committed himself to rebounding more in the playoffs and that gets me the ball more in the open court," said Nixon, "and that's where I'm at my best."

Just about all of the Lakers were at their best tonight and, for the first time in this series, more than seven of them got to play, although the only other player to get significant minutes was Mark Landsberger, who came in when Abdul-Jabbar got in foul trouble in the first half.

Riley also made some minor adjustments in the Lakers' trapping defense.

"The traps are the key to our defense," he said. "If you play it right, the only way to beat it is with good outside shooting and we feel they have only one really good outside shooter--Toney. We made him take those shots."

The adjustment the Lakers made in their trap, according to Nixon, was to wait longer to put it on and then not allow the 76ers to get the ball to the middle as they had done Sunday.

Los Angeles broke to a 6-0 lead and, after the 76ers tied the score at eight, outscored them, 10-2. The Lakers really never were threatened again.

With Abdul-Jabbar on the bench, Bob McAdoo scored 12 of his 14 points in the last 14 minutes of the first half, to make Abdul-Jabbar's absence as much of a pain than his presence.

Ahead by 12, the Lakers began the second quarter with an 8-0 run with Nixon and Michael Cooper each getting two fast-break baskets.

By then, the 76er offense was a two-man game with Toney and Erving. They combined for 21 of Philadelphia's 28 second-quarter points, with Toney getting 14.

Cooper's three-point shot at the buzzer gave the Lakers a 60-48 halftime lead. The Lakers made just seven jump shots in the half, scoring 45 points on layups, slam-dunks concluding a fast break and resulting foul shots.

Bobby Jones was no factor because of a painful hip pointer and took only one shot the entire game and failed to score in 26 minutes.

The Lakers clinched the game early in the third period, outscoring Philadelphia, 17-4, in the first five minutes for a 77-54 lead. Abdul-Jabbar had six of the points as the Lakers were stealing the ball, running and looking like they were having a great time at the 76ers' expense.