After 18 months of restoration, Bertha began a new life in the Sub Aqua Dive Centre in the city's Cameron St, moving to Dive HQ in Clyde St in 1980.
For the past 32 years, the huge single-cylinder compressor has been turning over slowly, filling untold thousands of 80cu ft dive tanks with air in 40 seconds.
But Dive HQ boss Kevin Hobbs said retirement loomed after the compressor's motor had caught fire. It would have cost $12,000 to replace burned parts and the 104-year-old machine was already costly to maintain.
Some parts were removed and Bertha was headed for the scrap heap until marine insurance assessor Sholto McCardle stepped in to save her, arranging for Atlas Cranes to donate a 60-tonne crane to lift the old compressor through the Dive HQ roof after Dixon Roofing had lifted the iron clear.
Ensura Building Services supplied a building and Northland Contract Boatbuilding provided store space for Bertha while the Packard and Pioneer Museum at Maungatapere decides whether it has room to offer her a home.
"If she doesn't go there the maritime museum at the Navy dockyard at Devonport in Auckland is interested in her," Mr McCardle said.
Meanwhile back at Dive HQ, they are filling dive bottles with a temporary compressor while they wait for the delivery of a small new machine with a 22cu ft a minute capacity, compared with Big Bertha's compression strength of 120cu ft a minute.