Attached is an article, worthwhile reading about the difference between problem solving and continuous improvement.
Although non-exhaustive, it provides insight on why initial Lean efforts seem to fade away after some time. Small and mostly individually driven improvements cannot reach a sustainable state unless a corporate buy-in is visible and in action. This requires recognized authority to support and institutionalize “Lean” as a company initiative by having functional experts, internal branding etc. Some local references can serve as a reference to prove this approach.
Read the article here