That’s the machine going blind. The glass scale — etched with micron-perfect graduations — had fogged, or cracked, or simply given up.
Then he called the service tech. The machine was possessed — not by demons, but by dust on a linear scale and a dying 5-volt supply. Would you like this turned into a short troubleshooting flowchart or a fictional machine log (timestamped error entries)? heidenhain error codes
Then came the one no machinist wants to see: That’s the machine going blind