Einmal noch Thomas Tomosy, den ich als Lehrer sehr verehre:

Know your limits: Many good people have had repair jobs end in ruin simply because they didn’t know when to quit. You must realize and accept that there are limits to what you can do.
Camera Maintenance & Repair, Book 1: Fundamental Techniques: A Comprehensive, Fully Illustrated Guide (English Edition) https://amzn.eu/d/cuPrHo2

Was natürlich nicht bedeutet, dass Grenzen für immer fest gezogen sein müssen