to NIMT trains, instead of running over the Marton - New Plymouth Line to Wanganui and the Palmerston North - Gisborne Line as far as Gisborne. By comparison, the Palmerston North-based JAs spent more time working freight trains, particularly with the arrival of the 88 seater railcars. Following the start of dieselisation in the 1960s, the locomotives migrated to Frankton Junction. While JA 1286 was briefly transferred to Auckland in the mid-1960s, it was felt it did not perform as well as the eleven Auckland-based locomotives and was quickly re-allocated to Frankton. After this, the locomotives were largely relegated to the old East Coast Main Trunk Railway between Hamilton, Tauranga and Taneatua, again largely on freight trains due to the reduction of passenger services from Taneatua to Te Puke, which was by now handled by the 88 seater railcars. Withdrawal and disposal Despite being a very young class, some of the North British JA class members were among the first of the J types to be withdrawn. The first of the class to be withdrawn, JA 1279, was withdrawn in 1964 and sent to Hillside Workshops minus at least one driving wheelset, taken to repair JA 1275 after it suffered an axle fracture while passing through Mercer that year. The rest of the locomotive then became a source of spares for the J and Hillside JA class locomotives in the South Island, with the oil-fired boiler being converted to coal-firing before being fitted to Greymouth-based J 1212 during a C grade overhaul. As the North British JAs were withdrawn, most were stripped of parts to keep the South Island J and JA class locomotives running, along with the remaining North British JAs which by then were based out of Frankton Junction. Several of the tenders from JA 1287, 1288, 1290 locomotives, transferred south in November 1966, which were in relatively good condition, were rebuilt to accommodate a coal bunker in place of the fuel oil tank and attached to J class locomotives whose original 1939-built tenders were life-expired. Other parts of the surplus North Island JA were also refitted, including the trailing trucks and approval was given to fit JA 1288 boiler. Most of the North Island JA were withdrawn too late in 1967 or early 1968, to be reprocessed, as A-grade South Island J overhauls had ceased with dieselisation, but JA 1281 boiler was refitted to J 1236 in