Cummins N14 Celect Plus Long Crank

N14 Celect Plus Has Long Crank Then Starts. Connected Scope To See Fuel Back Leakage. Found 1,2,3 and 6 have Back Leakage And Need Replacement. 5 Has Been Replaced Recently So We Used That One For Reference. Cylinder 4 Also Looked Well. I Also Checked For Possible O Ring Leakage And Found No Leakage.