Clowns tumbled, cheerleaders spun in front of the stage, and 52,000 beaming Americans, from toddlers to straw-hatted grandparents, basked in the good vibrations. It was the Beach Boys' first major concert since Interior Secretary James Watt won himself a presidential "Shoot-Yourself-in-the-Foot" Award last month by equating the band with a "hard-rock" element inimical to "wholesomeness." Now lead singer Mike Love surveyed the happy, sun-splashed throng at San Diego Stadium and called out, "It's so good to see all you undesirable elements here today!" From an upper tier, a banner fluttered: "Watt's wrong with the Beach Boys?"

On the surface, at least, nothing. They're hauling in an estimated $80,000 a pop, playing to capacity crowds following major league baseball games. More heartening to rock's boys of summer is the tentative return to performing of their muse and creative mainspring, the eccentric and reclusive Brian Wilson. As up-and-down as the surf itself, Brian first bowed out of touring in 1964, having grown deaf in one ear and somewhat stupefied by '60s self-indulgences—including, says brother Carl, LSD.

A notorious binger, Brian became obese and withdrawn in the 70s. He put his piano inside a huge indoor sandbox and for one two-year period never ventured out of the house. But recently the 40-year-old singer-songwriter-producer has kicked booze and a three-pack-a-day cigarette habit, and is sticking to a regimen that has peeled 100 pounds off his 6'2" frame. He now weighs in the "low 200s."

"I've been through a great deal of mental anguish," he says. "I felt like a fat slob. It was very embarrassing. I used to go onstage and it was scary. Now I'm getting used to it. I feel a little more confidence in myself."

Brian attributes his progress to the round-the-clock ministrations of Beverly Hills shrink Dr. Eugene Landy and his staff, who dictate Brian's every move, forbidding idleness, controlling everything he ingests, and recording his every word for discussion. "You lead a person to independence by first making him dependent," explains Landy of his technique, which costs $150 an hour. "We have someone with him 24 hours a day to help him develop a muscle he hasn't used—the muscle that enables you to say no."

Once before, in 1976, Brian signed up with Landy, but the band's former manager protested the cost, then $90 an hour, and canned him after one year. Backsliding, Brian reached such a grotesque state of sloth that Love, his first cousin, threatened to toss him out of the band if he didn't get help. This time, the Boys say, money will be no object. "We decided we're all willing to kick in if the cost becomes excessive," says keyboardist Bruce Johnston, 40.

Last year Wilson was divorced from Marilyn Rovell, his wife since 1965, but in that respect, he has nothing on his chums. Brother Dennis, 38, who has had his own bouts with the bottle (he was banned from several Venice and Santa Monica boîtes), married and divorced actress Karen Lamm twice, has been linked with Christine McVie of Fleetwood Mac, and recently had a son with his latest girlfriend, Shawn Love. Brother Carl, 36, who temporarily quit the band in 1981 because "the guys were not putting enough care into what they were doing," separated from his first wife, Annie, in 1977 and has since gotten a divorce. He now lives with Dean Martin's 26-year-old daughter Gina. Love, 42, and guitarist Al Jardine, 40, are currently toughing out divorces Nos. 4 and 1 respectively.

It hasn't been all Fun, Fun, Fun, but the group knows what Brian has meant to them. "He is the only guy that ever got us, as a band, to stretch," says Johnston. They're pulling for him. "If he never writes again but is at peace with himself," says Carl, "it'll be great." After four months of Landy's 18-month program, Brian is still shaky. A female associate of Landy's sat with him at the piano to steady him during the first few numbers of the San Diego concert. What are the odds of complete recovery? Considering past reverses, it may be safest to quote the title of one of Brian's hits from 1966: God Only Knows.