USING PIPE WRENCH W/CHESTER BAR ON GEAR PULLER TO REMOVE GEAR ON SHAKER. USING SLEDGE HAMMER TO DRIVE GEAR BACK ON. WENT HOME AT END OF DAY, EXPERIENCED PAIN IN NECK AND RIGHT SHOULDER SHARP P AIN PAIN WOKE HIM AT 300 AM WORSE COULDNT LIFT HEAD OFF BED, WENT TO EMERGENCY ROOM IN MORINING APPROX. 800 AM.