KiwiRail says it has resolved problems with new freight wagons built in China.
The 500 new flat-top wagons arrived only last year but by February, 44 were undergoing repair or maintenance.
KiwiRail says 24 are currently out of commission, which is within normal operating limits. Wheel slips were the chief problems.
Chief executive Jim Quinn says that overall KiwiRail is very satisfied with the wagons.
The 500 wagons were bought in two orders for $49 million. Letting the contract offshore led to 44 redundancies at the company's Hillside workshops in Dunedin.
KiwiRail announced last week it is selling Hillside because it does not have enough orders.