In this process of finding a new music director for the Bangor Symphony Orchestra, local patrons of the symphony have had the treat of hearing a 20th century piece, a romantic piece and a Beethoven symphony for each of this season’s concerts.

On Sunday at the Maine Center for the Arts, Glen Cortese of the Manhattan School of Music offered a program that included Samuel Barber’s Second Essay for Orchestra and Igor Stravinsky’s “The Firebird.”

He conducted them both with sweeping expression and clarity. The Barber was a particularly lively exercise in orchestral architecture, and Cortese showed his talent for zeroing in on the angles of this towering composition. What this rendition of the ballet lacked in passion, the orchestra made up for in volume and enthusiasm. The musicians clearly enjoyed the challenge, and the payoff was a rather agreeable and convincing performance.

As with the last two concerts, the first half of this program showed how the conductor can navigate in modern and romantic waters, and Cortese generally sailed smoothly.

But with the second half of the concert, in which he presented Beethoven’s Symphony No. 3 in E-flat (Eroica), Cortese hit some rough waters. It seemed, in fact, that Cortese had gone out for an intermission and returned with a different orchestra altogether. The sound, which was often limp and thin, did little to justify the subtitle of this work. And when an already long score moves at such a laggard pace, the result is simply boring.

The orchestra was not at its absolute best either, and many of the shouting cries of heroism came forth in murky or wobbly tones. It seemed as if the orchestra might be warming up through the first two movements, especially since the third suggested the type of fiery character of the symphony. Susan Heath and Patricia Eames on flute and Jo-Anna Tensa on oboe breathed life into this section, but the victory was marginal and not enough to thrust the entire performance into a convincing light.

It was an unfortunate about-face for a concert that seemed to get off to a good start.

A final note for those who noticed Lynn Brubaker in the position of concertmaster: Estelle Holly, who usually fills the first chair, is in Florida and will return for the next concert.