Officials are promising that the country's war memorial Carillon instrument in Wellington will not need to be disassembled for major repairs again.
The Carillon in Pukeahu Park is unable to play, and the belltower and adjoining Hall of Memories have been closed since February, after engineers discovered the bell tower and bell frames are both quake-prone.
This is despite years and millions of dollars of upgrade work - though the 2016-2018 $300,000 overhaul of the bell frames themselves was hamstrung when officials chose to save $60,000 by not replacing all the steel frames that it had been recommended needed fixing.
This previous upgrade work generated corrosive concrete dust that played a big part in damaging the Carillon instrument and bellframe, according to newly-obtained documents.
Now, more strengthening of tower and frames must be done by a 2022 deadline.
But the Ministry for Culture and Heritage denies this could force a second overhaul of the Carillon instrument.
"The anticipated future seismic work will inevitably involve some concrete drilling and cutting," Manatū Taonga Te Pae Mahara manager Brodie Stubbs said in a statement.
"Dust management and protection of the instrument will mitigate adverse effects.
"Only a minor amount of work will be required to reinstate full functionality of the previously-renovated Carillon instrument following the seismic upgrade."
RNZ has asked the ministry to provide evidence to back up the statement that only minor work would be needed.
Five years ago, when the instrument was "barely functional", the head carillonist urged the ministry to finish all concrete drilling "prior to renovation work on the Carillon instrument", the documents show.
Stubbs said dust was only one damaging factor - and vacuum extraction could minimise its spread. The other factor was rust which had been dealt with.
The documents show rust was removed and steel repainted. But some of this steel had been tagged to be replaced entirely but was not. It is still there in the quake-prone frames.
"There is not always a simple, straightforward sequence for undertaking maintenance work," Stubbs said.
The National War Memorial was a complex structure - "an important heritage building performing an important social service".
"Sometimes short-term fixes must be made in order to maintain access to the building or to ensure playability of the Carillon for commemorative events."
However, the ministry's "short-term fixes" have failed to maintain access or keep the Carillon playable, and the War Memorial's key buildings remain closed.