NEW YORK — James Levine’s motorized chair rose in the orchestra pit and turned to allow him to face the audience, prompting a 30-second ovation that began the evening. He tapped his heart and blew a kiss to the nearly sellout crowd.

There has been renewed focus on the health of the 72-year conductor, who made his Metropolitan Opera debut in 1971 and has been its chief musical force since the 1973-74 season. After he exhibited an erratic baton technique during performances last fall and withdrew from a new production of Berg’s “Lulu,” the Met nearly announced the music director’s retirement in February. But the company held off to await results of a change in medicine to treat what the Met has said is a neurological disorder related to Parkinson’s disease.

Friday night’s performance of Verdi’s “Simon Boccanegra” starring 75-year-old Placido Domingo was Levine’s first scheduled opera since Jan. 7, and the pair got warm welcomes — with the audience also applauding when Domingo made his first entrance.

Levine weaved together an exemplary performance of sweep and gravitas, but there were worrisome signs. As he did last fall during Wagner’s “Tannhaeuser” and Johann Strauss Jr.’s “Die Fledermaus,” Levine tilted toward the right for much of the performance and rocked from side to side in his chair. His hands were in constant motion. During a several-minute break between the second and third acts, he beat his baton up and down as he spoke with members of the orchestra while waiting for the set change to be completed.

During the 1990s, his baton technique grew more minimal. He signaled precise downbeats with his right hand and used his left to cue singers and the chorus and to shape texture.

Levine had clear downbeats Friday during solo portions, duets and trios but seemingly extraneous beats appeared when the chorus was on stage for the council chamber scene that closes the first act. His left hand was in near-constant lateral movement, fist clenched at times, and it was difficult to discern its cues.

Levine has conducted from a chair since late 2001. And after tremors in his left arm and leg became noticeable in 2004, he said they began a decade earlier. His health worsened in 2006, when he tripped and fell on the stage of Boston’s Symphony Hall during ovations that followed a performance and he tore a rotator cuff, which required shoulder surgery.

He had an operation in 2008 to remove a kidney and another in 2009 to repair a herniated disk in his back. Surgeries caused by spinal stenosis followed in May and July 2011, and he had another operation that September after falling and damaging a vertebra, an injury that sidelined him until May 2013.

Levine, who has conducted the Met more than 2,500 times, is scheduled to lead four more performances of “Boccanegra” through April 16 followed by five performances of Mozart’s “Die Entfuehrung aus dem Serail (The Abduction from the Seraglio).”

Domingo, a celebrated tenor who made his Met debut in 1968, sang the baritone title role of “Boccanegra” for the first time in 2010. While he is not a natural baritone and lacks some power on lower notes, he overcomes that with unmatched artistry that creates a far more polished character than many of his younger colleagues. His duet with soprano Lianna Haroutounian, who sang Amelia Grimaldi, was deeply affecting.

Tenor Joseph Calleja was Gabriele Adorno, Domingo’s role when Elijah Moshinsky’s production debuted in 1995. Bass Ferruccio Furlanetto (Jacopo Fiesco) rounded out the strong cast.

Levine is scheduled to conduct 31 performances of four productions at the Met next season, but Met General Manager Peter Gelb said in February it was too soon to say whether Levine would be up to it physically. Levine’s health seemingly remains the company’s biggest preoccupation.