I designed this power supply five years ago and it is still working perfectly in thousands of devices but now they want me to redesign it because the components are going end-of-life and I cannot find exact replacements.
More people experience this than they realize.
Your old design still works great, but now you have to rebuild it and can't find the parts.
“Where Are You with Engineering — Electrical (Physical Systems)?”
If this sounds familiar, the Library can help you find the bigger picture.