UTTARKASHI, India (AP) — Rescuers racing to evacuate 41 construction workers who have been trapped in a collapsed tunnel in northern India for nearly two weeks are hoping to resume drilling on Friday after a mechanical problem a day earlier forced them to halt, officials said.

The platform of the drilling machine, which became unstable while boring through rock debris, has been fixed, Bhaskar Khulbe, a former adviser to the Prime Minister’s Office, said at the accident site.

But before they can resume drilling, rescuers are manually digging through the debris to remove pieces of metal to avoid damaging the machine, said Kirti Panwar, a government spokesperson.

Drilling was also paused on Wednesday after the boring machine hit a metal girder, causing some damage to its blades and a six-hour delay as rescuers worked to clear the obstacle.

The workers have been trapped since Nov. 12, when a landslide in mountainous Uttarakhand state caused a portion of the 4.5-kilometre (2.8-mile) tunnel they were building to collapse about 200 meters (650 feet) from the entrance.

Rescuers began drilling through the entrance of the tunnel to reach them but have been stymied by debris and technical problems. The mountainous terrain has proved a challenge for the drilling machine, which broke down earlier as rescuers attempted to dig horizontally toward the trapped workers. The machine’s high-intensity vibrations also caused more debris to fall.

As efforts stretch into the 13th day, rescuers have drilled through 46 meters (151 feet) and need to excavate up to 12 metres (40 feet) more to create a passageway, Panwar said.

Rescue teams are inserting and welding together pipes through which the trapped workers are to escape to freedom. About 46 metres (151 feet) of pipes have been put in so far, he said.

Members of the National Disaster Response Force will then bring out the workers one by one on stretchers that have been fitted with wheels.

Officials earlier hoped to be ready to start bringing the workers out on Thursday, but now that won’t happen until Friday evening at the earliest.

Authorities have been supplying the trapped workers with hot meals made of rice and lentils through a 6-inch (15-centimetre) pipe, after days in which they survived on dry food sent through a narrower pipe. Oxygen is being supplied through a separate pipe.

Officials earlier released a video after a camera was pushed through the pipe showing the workers in their construction hats moving around the blocked tunnel while communicating with rescuers on walkie-talkies.

Most of the trapped workers are migrant laborers from across the country. Many of their families have traveled to the accident site, where they have camped out for days to get updates on the rescue and in hopes of seeing their relatives soon.

Haridwar Sharma’s brother, Sushil, is among those trapped.

“We are all waiting here, hoping they come out. It is not in our hands … the administration is at it, the machinery is there. With God’s blessing, we are hopeful,” he said.

Large numbers of pilgrims and tourists visit Uttarakhand’s many Hindu temples, with the number increasing over the years due to continued construction of buildings and roadways.

The tunnel being built by the workers is part of the Chardham all-weather road which will connect various Hindu pilgrimage sites. While a flagship project of the federal government, some experts saying it will exacerbate the fragile environment in the upper Himalayas where several towns are built atop landslide debris.