I've got a QSB 6.7 Cummins (C200D6E). The generator has been making extreme high noise during cranking and the issue was found out to be of piston. However upon getting rid of the head, the valves were found to be damaged. Now the question is, I've got technicians and I'm about to get the tools needed. Can this overhauling be done by us by following the step by step procedure in the service manual or is there more to it? I'm a newbie in the generator maintenance and I apologize for making any mistakes. Please help me