▁the ▁tunnel - bor ing ▁machine ' s ▁capabilities ▁were ▁in ade qu ate ▁for ▁the ▁project ▁and ▁should ▁be ▁ex cluded . ▁ ▁It ▁is ▁unclear ▁what ▁triggered ▁the ▁damage ▁to ▁Ber tha ' s ▁main ▁bearing . ▁Problem s ▁with ▁the ▁se al ▁system ▁appear ▁to ▁date ▁back ▁to ▁the ▁machine ' s ▁initial ▁testing ▁in ▁Japan , ▁when ▁the ▁se al ▁assembly ▁was ▁dam aged ▁and ▁required ▁rep airs . ▁However , ▁Hit achi ▁Z osen ▁general ▁manager ▁So ichi ▁T aka ura ▁later ▁stated ▁that ▁" there ▁was ▁nothing ▁wrong ▁with ▁the ▁se als ▁in ▁the ▁original ▁machine ", ▁not ing ▁that ▁Ber tha ▁appeared ▁to ▁function ▁properly ▁before ▁striking ▁the ▁well ▁cas ing . ▁W SD OT ▁disput ed ▁this , ▁and ▁stated ▁that ▁the ▁well ▁cas ing ▁was ▁not ▁responsible . ▁ ▁Res umption ▁of ▁dig ging ▁and ▁subsequent ▁activities ▁ ▁On ▁December ▁ 2 2 , ▁ 2 0 1 5 ▁at ▁ 1 2 : 3 0   a . m ., ▁the ▁machine ▁res umed ▁dig ging ▁ ▁through ▁sand ▁pou red ▁into ▁the ▁recovery ▁pit . ▁By ▁January ▁ 4 , ▁Ber tha ▁had ▁tra ve led ▁ ▁of ▁its ▁planned ▁ ▁route ▁from ▁So Do ▁to ▁South ▁Lake ▁Union . ▁On ▁January ▁ 6 , ▁ 2 0 1 6 , ▁Ber tha ▁broke ▁through ▁the ▁concrete ▁access ▁v ault ▁and ▁began ▁dig ging ▁through ▁normal ▁soil . ▁Dig ging ▁was ▁halt ed ▁once ▁again ▁on ▁January ▁ 1 2 , ▁