The power interconnector was damaged when routine maintenance was begun on 24 March, with Basslink saying at the time that a third-party contractor had damaged a piece of equipment and that the interconnector would be up again by 14 April.
In a statement issued overnight, Basslink said a high-pressure system within a piece of equipment at the Victorian converter station had been repaired.
"To return the interconnector to service, we require specialised expertise and equipment to be brought in to re-pressurise this equipment. It is a highly technical exercise," the company said.
Basslink is in the midst of a dispute with the Tasmanian Government over an earlier outage in December 2015 which lasted for six months. The government is seeking damages of $122 million; Basslink denies that it was responsible for the outage.
The Basslink statement said: "This incident is unrelated to the outage in December 2015 and the ongoing dispute with the state of Tasmania."
Contacted for comment, Hydro Tasmania, the Tasmanian Government body that is the predominant electricity generator in the state, said Tasmania was well-placed to manage a Basslink outage lasting up to 31 May.
“The extended Basslink outage is not ideal. But it doesn’t meaningfully affect Tasmania’s energy security,” Hydro Tasmania chief executive Steve Davy said in a statement.
“Autumn has produced good above-average inflows so far. We expect to manage comfortably without the ability to import.
“Hydro Tasmania storages were at 37% on Monday. That’s an extremely secure level as we approach the wettest months of the year. It’s also well above the High Reliability Level set by the Energy Security Taskforce."
The statement added that the Combined Cycle Gas Turbine at the Tamar Valley Power Station was not currently operating, but available at 10 days’ notice. The station also has about 150 megawatts of quickly-accessible gas generation.