Jerry Buss' waning enthusiasm for his stumbling Los Angeles Kings has reached the point where Buss has agreed to sell his 51 percent of the club to Bruce McNall, the club president who already owns the other 49 percent.

There's no questioning McNall's enthusiasm.

He offered the players $1,000 bonuses between periods of a game in Buffalo earlier this season, if they could beat the Sabres. They didn't and McNall reportedly was censured by NHL President John Ziegler.

Buss, who expressed interest in a baseball or football franchise, once considered the Kings a Stanley Cup contender. When they got off to a fast start in 1980, Buss said they ought to win the Cup, a remark that infuriated Bob Berry, the coach at the time. Berry currently is selling cars in Los Angeles. 'I'd Get Spanked'

Goalie Bob Mason, who received a four-year contract worth $1.4 million from the Chicago Blackhawks, was willing to sign a new pact with Washington last February at half that figure, but he said he did not receive an offer from the Capitals until season's end. Mason's value ballooned after a superb showing in the playoffs. Chicago Coach Bob Murdoch passed out midseason grades to his players the other day and Mason, 9-12-3 with a 4.29 goals-against mark, commented, "If I took this home to my mom, I'd get spanked." . . .

When a player is traded from a Canadian team to a U.S. team, he completes his current contract in U.S. dollars, which constitutes about a 30 percent raise. Defenseman Neil Sheehy, in signing his previous contract with Calgary, agreed to a reduced salary to be paid in U.S. dollars because, "I eventually wanted to go to a U.S. team in the East and I didn't want to price myself out of the market." Sheehy got his wish when he was dealt to Hartford, but now says, "I have mixed feelings, because Calgary is good enough to win the Stanley Cup and I'd have liked to be part of it." Ready for Questions

Philadelphia's Tim Kerr is recuperating on schedule from all those operations on his left shoulder and is expected to return early in March. The determining factor is when the left shoulder is 85 percent as strong as the right one. Kerr has been helping Coach Mike Keenan and said, "It's a different experience. You don't really see the game very well, but it's nice being with the guys. If they have a question, I'm there." . . .

Brian Mullen, the Rangers' right wing, was a stickboy for the club when it played Montreal in the 1979 Stanley Cup final. "I'm playing with some of the guys who were on that team and I learned a lot watching them, but Bob Johnson at Wisconsin really taught me the game of hockey," Mullen said . . .

Johnson, former Philadelphia coach and general manager Keith Allen and Boston broadcaster Fred Cusick will share the Lester Patrick Trophy for service to U.S. hockey at the all-star dinner Feb. 8. Get Off the Stick

Calgary Coach Terry Crisp likes to pass along homilies he learned as a player under Fred Shero in Philadelphia. Crisp said, "I see guys in the stick room discarding sticks and trying others and I tell them not to look at the lumber. Freddie used to say, 'Don't blame the gun, blame the triggerman.' "