Instead, the ministry stuck by doing a stopgap fix to buy time until an intended complete overhaul in 2021.
The work to date had been "focused on keeping the instrument playable, as much as possible, while working around a range of other major seismic upgrades and maintenance to the tower structure", the ministry's manager of memorials and taonga, Brodie Stubbs, told RNZ in a statement.
This approach has backfired.
The bell frames took almost two years to fix instead of two months, keeping the tower closed till Anzac Day 2018.
And it closed again in February this year after engineers found the frames are earthquake-prone, rated at just 15 per cent of Standard, despite $325,000 of work from 2016-18.
The tower structure, too, is rated at only 15 per cent, despite a 2012-16 strengthening project. That work did raise the quake standard to 100 per cent at the adjacent Hall of Memories, but it is closed too because it is accessed via the tower.
The RSA has said it is "sad" and "disappointed" the bells can't play.
RNZ obtained the latest documents after the ministry failed to release them, along with other material it did provide, following an Official Information Act request.
"This was an oversight on our part rather than anything deliberate and we apologise for this," Stubbs said.
Yet the documents themselves show the ministry knew about some of the documents that were not released, at the time it responded to RNZ's OIA.
Playable - by 2015
As early as 2014, the ministry had hopes the Carillon could be playable again by Anzac Day 2015, the documents show.
But by June 2015, the list of what it knew was wrong was growing:
• All three steel frames were corroded, requiring partial or full replacement, especially the upper treble frame on top.
• Advanced corrosion on all bells, some mounting brackets, bolts and retaining nuts.
• Widespread contamination of steel with concrete dust from all the seismic work.
Late that year, officials decided against replacing all the frames.
However, Hurd "believes in order to realise the best value for money over time ... this decision should be revisited", the documents said.
Hurd has worked on many carillons worldwide.
"In particular, Mr Hurd is concerned that effecting repairs to the instrument without addressing the frame issues, will lead to water dripping through the frame compromising any repairs undertaken (so they will fail sooner than would otherwise be expected)."
Rust-impregnated water had already compromised galvanised components.
The ministry told RNZ that Hurd had not challenged its decision, just "expressed a view that full replacement would be the best value for money over time".
Engineers told officials back in 2011 to do a full seismic assessment of the bell frames, but this occurred only in 2019-20.
In 2016, it went ahead with refurbishment in the absence of a seismic assessment.
"At some point it would be useful to get engineering advice on the bell frame, how long it is expected to last for, and seismic issues," the ministry's project manager wrote in October 2016.
This was one month before the Kaikōura earthquake and three years after the Seddon quake rocked the capital.
By then, the Carillon steelwork contract was already six months along, and workers had exposed so much corrosion and defects that the original tender of $47,000 in May, had been raised to $61,000.
'Fixed budget' limits steelwork
By September, Stevensons Structural Engineers said the frames needed an extra $140,000 of work.
After negotiations with officials, this was cut almost in half to $80,000, by leaving out 14 of 16 items of work on the lower bell frame.
The omitted work was "not so critical given the ministry's long-term plans", Stevensons said.
The ministry was optimistic: "This work is expected to be sufficient for the next five years, when a total overhaul of the Carillon will be done," a heritage projects manager told the acting chief executive Cath Atkins.
Ultimately, the refurbishment took up a large chunk of those five years, but cost less than planned - $325,000 against a budgeted $334,000, with a lot of that paid to Fletcher Construction - by skimping on the steel.
"Certain angle bracing sections in the lower belfry that had been identified for replacement were, instead, retained, cleaned and painted," a ministry document said.
In the upper frame, "ultimately, about 20 per cent of steel ... was replaced outright, with constraints on doing further replacements imposed by the fixed budget provided for the work".
The 2019-20 detailed seismic assessment identified two key structural weaknesses in the lower bell frame, including "braces buckling under load".
Rust 'bubbling through'
By contrast, in December 2015, the Pukeahu Precinct Programme Board, which at that stage had hoped for an Anzac Day 2016 opening, said "its preference was to have the repair done correctly rather than have any deadline hindering any work".
As late as January 2018, rust was still "bubbling through and paint is not sticking" on some steel, because it hadn't been prepared properly; some head stocks were bowed; and bell frame angle struts still "require work", though just what is not clear.
Less than four years since the steelwork began, the Carillon was shut once more in February.
A peer review of the detailed seismic assessment is expected by the end of August, "so we can confirm all the recommendations and gain a better understanding of the costs involved" in finally fixing the tower and bell frames, Stubbs said.
The ministry has less than two years to get it fully strengthened, under earthquake-prone building laws.
"While the steel bell frame structures are not considered inherently unsafe, their eventual replacement is inevitable, given their age and level of exposure to the elements," Stubbs said.
RNZ understands the upgrading of some of the tower's services and stairways alone could cost $1 million, which does not account for the seismic strengthening itself.
The 2012-2016 seismic work created concrete dust which corroded the bell frame steel.
