9 6 , ▁one ▁of ▁them ▁was ▁allocated ▁to ▁O ' ok ie p ▁for ▁sh un ting ▁and ▁local ▁work , ▁including ▁service ▁as ▁construction ▁locomot ive ▁while ▁the ▁N ab abe ep ▁branch line ▁was ▁being ▁built , ▁and ▁then ▁as ▁branch line ▁power ▁after ▁the ▁line ▁was ▁opened ▁in ▁late ▁ 1 8 9 8 ▁or ▁early ▁ 1 8 9 9 . ▁The ▁locomot ives ▁were ▁rot ated ▁occasionally ▁and ▁all ▁three ▁had ▁service ▁sp ells ▁as ▁the ▁O ' ok ie p ▁engine . ▁By ▁ 1 9 1 0 ▁they ▁were ▁no ▁longer ▁used ▁on ▁the ▁N ab abe ep ▁line ▁since ▁the ▁trains ▁had ▁become ▁too ▁heavy . ▁ ▁As ▁a ▁result ▁of ▁the ▁poor ▁quality ▁of ▁water ▁in ▁the ▁region ▁and ▁t ough ▁working ▁conditions , ▁the ▁three ▁locomot ives ▁suffered ▁major ▁problems ▁with ▁their ▁fire box es ▁and ▁tub es ▁and ▁rep lac ements ▁were ▁required ▁fairly ▁frequently . ▁As ▁an ▁example , ▁the ▁engine ▁Juan ita ▁required ▁a ▁new ▁bo iler ▁and ▁fire box ▁in ▁ 1 8 9 5 , ▁just ▁eight ▁years ▁after ▁entering ▁service . ▁The ▁cond ens ing ▁system ▁was ▁also ▁never ▁successful ▁due ▁to ▁the ▁high ▁ambient ▁temper atures ▁in ▁the ▁region . ▁ ▁They ▁remained ▁in ▁service ▁on ▁lower ▁section ▁traffic ▁on ▁the ▁main line ▁until ▁at ▁least ▁ 1 8 9 9 . ▁At ▁some ▁stage ▁between ▁then ▁and ▁late ▁ 1 9 0 6 , ▁after ▁they ▁had ▁been ▁replaced ▁on ▁main line ▁service ,