Abstract: An August 18, 1984, during the early part of the second shift, Employee #1, a maintenance mechanic, was assigned to clean a screen on a vertical core machine. The second shift was a down shift. Cleaning the screen was preventive maintenance, performed about 12 times a year. Employee #1, after preparing the machine for screen removal, climbed into the machine between the dies. The hydraulic and electrical power had not been deenergized. He started to remove parts of the machine to get at the screen. A light curtain that was functioning at the time of the accident protected the point of operation. While the employee was in the die area, beyond the light curtains, the machine functioned and the dies closed on his head, killing him. Employee #1 was an experienced mechanic, familiar with the company's lockout procedure. He had two locks in his toolbox.