How do I cope when my precise work is only noticed when it fails?

You have mastered something quiet and thankless. When your work is perfect, no one sees it. When one part fails, everyone does. That is a lonely kind of excellence, and being tired of it is fair. The recognition you have earned mostly lives in the absence of problems no one knows you prevented. Here is the truth others miss: the value of your work is real whether or not it is seen. Every good part that runs down the line, every machine that does not jam, every customer who never knows your name, is your doing. Praise is pleasant, but it was never the reason the work mattered. Still, you should not have to carry it entirely alone. Find one person, a younger worker or a peer, and let them see what you actually do. Teach them what you watch for. Being witnessed by even one person who understands is worth more than applause from a crowd that never will.