[1][11] Soon after entering service, problems were experienced with failing connecting rods, big end bearings breaking up as well as cracks developing in the motion girder of the Alligator crossheads.

After investigations by SAR engineers with assistance from the South African Council for Scientific and Industrial Research, the crossheads, slide bars and coupling rods were modified.

When new, the tapered Timken crankpin roller bearings soon became notorious for throwing their lubricant onto the underside of the boiler, from where it ran down to the lowest point and dripped onto the coupled wheel tyres along the way.

[10] The Class 25NC initially served on the unelectrified mainlines from De Aar via Kimberley to Welverdiend.

They were pooled from their introduction and were run through from De Aar to Welverdiend and vice versa, recoaling at Warrenton.

After electrification was extended from Welverdiend to Klerksdorp, they ran from there to De Aar, still recoaling at Warrenton.

Later they also worked from Kimberley via Bloemfontein to Harrismith in the Free State while some joined the Class 25 condensers on the line from De Aar via Beaufort West to Touws River.

[4][13] When the line south from De Aar was dieselised between 1973 and 1974, the Class 25 condensers working there were moved north to work the section from De Aar to Kimberley, where they replaced twenty-two Class 25NCs which were then relocated to Bethlehem in the Free State.

Locomotives with all four characters neatly in line and centred were therefore usually identifiable as original Class 25NCs.

The primary objectives of the project were to improve the combustion and steaming rate, to reduce the emission of wasteful black smoke and to overcome the problem of clinkering.

Passed boiler test July 2024 Operational Operational During 1988 a severe motive power shortage was experienced by the National Railways of Zimbabwe and discussions with South Africa revealed that numerous class 25NC 4-8-4, had been recently withdrawn from service and were available for either hire or purchase.