Greater Manchester Police (GMP) said officers examined a tip in Bury as they try to locate a blue suitcase used by suicide bomber Salman Abedi.
Twenty two people were killed and hundreds injured when Abedi detonated explosives after an Ariana Grande concert at the arena in May last year.
Officers carried out a search of the tip in the days after the bombing and have returned to look at a new area.
An image of 22-year-old Abedi wheeling the case in Manchester city centre on the day of the attack was previously released by police.
At the time, detectives said there was “no reason to believe the case and its contents contain anything dangerous” but asked people to be cautious.
They added that the suitcase was a “different item than the one he used in the attack”.
Questions remain over the bombing as officers try to establish whether Abedi acted alone or if anyone could be prosecuted.
Some 23 people have been arrested as part of the investigation but no one has been charged.
A hundred officers are still working full-time on the inquiry.
Abedi’s younger brother, Hashem, was detained in Libya shortly after the attack but he remains in the custody of a militia group in Tripoli.
Both brothers had travelled to Libya in April 2017, before Salman Abedi returned alone and carried out the attack on 22 May of that year.
The UK has requested Hashem Abedi’s extradition but it is not clear if or when that will happen.
Last month, some of the survivors and relatives of victims of the attack marked the first anniversary at a service at Manchester Cathedral attended by the Duke of Cambridge.