[jclark003]

Cummins can give you a better answer but it doesn't sound right that your engines are slowly rolling over several/5 turns before lighting. I can't imagine any starter surviving long slow cranking that much. Assuming the PO didn't install deep cycle batteries you may want to check the battery cables / connections as any one can cause the problem described. if they check out maybe load test the starter(s). By comparison if I don't parallel my Cats slow crank for maybe a second or two and then start right up. When paralleled they start right up with almost no hesitation even when cold. Good luck