What happened to the Z-axis drop?

Experience: If it is an old machine tool that has been in normal use for many years, the motor brake is generally worn out, and the servo motor brake needs to be repaired. In a static state, the load on the Z-axis should not exceed 60%. If the load is too high for a long time, the motor will overheat, which will cause wear and tear in the brake, which will cause the brake to fall due to lack of tightening.