Broadway tradition dictates that the show must go on. But in Andy Gibb's case, he didn't always go on with it. By any standard, his tenure in the title role of the musical Joseph and the Amazing Technicolor Dreamcoat was one of the most erratic in the history of the Great White Way. A chronic absentee, Gibb was a no-show at his dress rehearsal and missed an embarrassing 12 performances after opening on Dec. 1 to generally favorable notices. "When Andy was at the theater, he was a joy," says producer Zev Bufman. "But he wasn't there enough. It wasn't fair to the audience." Exasperated when Gibb skipped an entire week of performances last month, Bufman sacked the 24-year-old former teen heartthrob.

Gibb at first blamed his absences on colds and the flu. But later he confessed that he just didn't have the stamina for eight grueling performances a week. "He's very unhappy about it," says Andy's publicist, Michael Sterling. "Andy loved being in the show, he loved the company of the other actors. He just took on something he couldn't handle."

That seems to be a pattern in Gibb's life. Andy missed several performances when he played Joseph in Philadelphia before joining the Broadway cast, and he frequently called in sick while appearing in The Pirates of Penzance two years ago in L.A. Confides one Hollywood veteran associated with Penzance, "Andy doesn't understand the rigors of stage performing." Adds Bufman, "Elizabeth Taylor went on the stage in a wheelchair in Little Foxes. That's the norm. In the theater, missing performances is reserved for the dying."

For Gibb, even the pink slip was not without precedent. Last spring the producers of TV's Solid Gold, the syndicated musical variety program, fired Andy as co-host for missing too many tapings. That time Gibb blamed his poor attendance on sultry Dallas star Victoria Principal, the older (now 33) woman who had rejected his love. "I thought so much of the girl. When we broke up I gave up everything," Gibb confided in a Good Morning America interview. "I didn't care about life."

Andy consoled himself with cocaine. Drugs, in fact, were responsible for the end of his year-long relationship with Victoria. "Our breakup was preceded and precipitated by Andy's use of drugs," says Principal. "I did everything I could to help him. But then I told him he would have to choose between me and his problem." Andy has denied he still uses cocaine, and no one will say if drugs contributed to his Broadway troubles. The Joseph cast believes Andy suffered from an overdose of fear. "I hear he spent most of his time in his hotel room in front of the TV," says one actor. "I guess he was frightened and insecure. That's what happens when you're the baby brother of the Bee Gees."

Though Andy's absenteeism was a source of tension, his fellow cast members remain mostly sympathetic. Gibb had given Christmas gifts to everyone in the show: leather wallets for the men and pens with tiny digital clocks for the women. He picked up the check at restaurants and often invited friends in the cast to share his car, a shiny limo, complete with chauffeur.

It was precisely Gibb's ebullient good nature that kept Joseph's promoters hoping he would mend his ways. But after the star missed all the holiday week performances, Bufman called him in for a chat. "He promised me he wouldn't miss another," recalls the producer. "He said, 'If I do, you won't even have to call me, I'll be gone.' "

And so, eight days later, he was. After his dismissal, Andy and his mother, Barbara, who was in New York to see Joseph, flew immediately to L.A.; Andy is now resting at his Malibu home. Meanwhile in Shubert Alley, Bufman is searching for another star to boost ticket sales. It is an assignment he does not underestimate. "Of the five Josephs we've had so far," he concedes, "Andy was definitely the best actor."