The answer to 'when to replace troubleshooting' is that you should replace your troubleshooting equipment when it is no longer functioning properly or accurately. This typically happens when the equipment has reached the end of its lifespan, has been damaged, or is no longer able to keep up with the demands of your electrical system.
As an electrical technician, I recommend replacing troubleshooting equipment every 5-10 years, or sooner if you notice any issues with its performance. This ensures that you have the most up-to-date and reliable tools to accurately diagnose and fix any electrical problems in your home.