The actual problem is Boeing made more changes from the 737 base and the checks for this changes were nod done properly because FAA didn't do it's job. Now if

The actual problem is Boeing made more changes from the 737 base and the checks for this changes were nod done properly because FAA didn't do it's job. Now if FAA and other international agencies check everything from scratch you will find all this hidden problems. Now imagine you are hired to check the plane systems, would you sign on subsystem X because it worked fine in the old 737 or use your brain and experience andcx flag all potential issues you see.