Afternoon Shift Shut belts off at about 3:20 to replace a bad roller. After the roller was replaced the belts were restarted and the beltmen checked belts as they were starting, all started down to # 16. Beltman went into # 16 drive and tried to start the belt but it would not start. A beltman went to the tail to check for a plug and found the roof fall (4:20 pm)