The 5'9" driving wheels proved too large for the steep gradients to which they were assigned, and a follow-up order for four, numbered 32-35, were built with 5'6" driving wheels. They were reclassified in 1889 as the G class before being withdrawn in the 1890s.
After being stored for ten years, all members of the G23 class were rebuilt as 4-4-0s at Eveleigh Railway Workshops with Belpaire boilers and four wheel Bissell leading bogies. They were renamed the Cg class in view of the similarity of the rebuilt locomotives to the C class 4-4-0s of 1879.[3][4] As part of the 1924 reclassification scheme, all 13 were reclassified as the Z14 class and renumbered 1401 to 1413.[2]
The last in service was 1412 which was retired in 1948. The last recorded as condemned was 1405 in 1950.[2][4] Scrapping of the class commenced in 1937 and was concluded in 1952.[5]