Narendra Mohan, the area officer of the DHR, said daily services between NJP and Darjeeling halted in January when one of the four diesel engines had developed problems.
"We had to run the services on alternate days, instead of everyday, because one of the diesel engines had developed a snag and was sent for repairs. We were short of engines and we had to reduce the number of trips on the route. Since January, we have been operating the trains on Mondays, Wednesdays and Fridays," Mohan said.
"But the engine has been restored and is back with the DHR. We will conduct trial runs to see if it is functioning properly and will commence regular services from NJP to Darjeeling by next week," he said.
Additional coaches have been attached to toy trains on the Darjeeling-Ghoom route since May 19 to cater to tourists.
"Normally, there are two first-class coaches but now there are four. The footfall of tourists has increased in the past one week. Two coaches were not enough," Mohan said. "We are planning to keep the additional coaches till June."
The four coaches can ferry around 120 passengers and the cost is Rs 630 per person.