Unforeseen factors with the Bethesda Metro station’s elevator rehabilitation project will delay the reopening of the elevator for about three weeks, a WMATA spokesperson said Thursday.

The lone street-to-platform elevator to one of Metro’s deepest underground stations was scheduled to be back in service in October. The elevator has been out of service since the project started in late May.

WMATA spokeswoman Caroline Lukas said two developments have extended the length of the project: Technicians realized they needed certain components that were not immediately available and workers did not realize the correct sequencing of work for one of Metro’s deepest elevators until after the project began.

The 106-foot-deep elevator is a bigger project than most elevator rehabilitation jobs on the system, Lukas said. It’s also the first time the elevator has been modified since the Bethesda Metro station opened in 1983.

“We know that the elevator is important to customers who use Bethesda Station,” Lukas said, “and be assured that we are working to return the elevator to service as quickly and as safely as possible.”

Since May, Metro has offered free shuttle service to the Medical Center station for disabled customers or other passengers unable or unwilling to use the station’s escalators, which at 212 feet are the second longest in the Western Hemisphere.

In September, WMATA spokesman Dan Stessel said Metro had a technician assigned to the station to quickly deal with any escalator issues because of the out-of-service elevator.

The escalators are also scheduled to undergo major work. Metro wants to begin the tricky and time-consuming process of replacing the three escalators in early 2014, though Montgomery County officials were hoping for an earlier start date.

The length and complexity of the escalator replacement project is why Metro elected to undertake the elevator rehabilitation project first, Stessel said.