If the ground zero redevelopment project were an orchestra, it would be making beautiful music, Port Authority executives said yesterday in an upbeat assessment of construction at the site.

But executives also acknowledged that even with most pieces falling into place after years of delays, ongoing problems with the dismantling of the former Deutsche Bank building following a fatal fire there last month have the potential to strike a sour note.

Nearly three weeks after two firefighters died in the abandoned building, which was irretrievably damaged on September 11, 2001, the agencies overseeing the taking-down of the structure have yet to determine how much longer the dismantling will be delayed.

“We’re waiting to understand exactly what the impact will be,” the Port Authority’s executive director, Anthony Shorris, said.

About half a dozen federal, state, and city agencies, including the FDNY, are currently rewriting portions of a deconstruction plan that originally took years to complete.

Since the fire, they have been meeting daily to come up with a consensus on issues such as whether to reseal the building to keep toxic dust from escaping — something the Environmental Protection Agency has demanded, but which the board chairman of the building’s owner, the Lower Manhattan Development Corporation, Avi Schick, suggested yesterday is negotiable.

Mr. Schick also said yesterday for the first time that his agency was “seriously looking at” doing the decontamination and deconstruction of the building separately in order to assuage community concerns about safety.