Verify that the action plan that is implemented does indeed prevent recurrence of the same NCE. Plan a mock run-through of any changes made to see if the outcome is as expected. Determine how you will measure the improvement. Equally important is to demonstrate that the new action plan does not adversely affect the product/service. Does the action plan fix one problem but yield new ones? If there is still potential for failure, the action plan must be reviewed and analyzed again.
Verification is a necessary part of problem solving.