#44 GYP FEEDER WAS PLUGGED AND COULD NOT UNPLUG FROM BELOW. EE WENT ON TOP WHERE FLOOR WAS SLIPPERY AND LIGHT WAS LOW. HE WAS UNAWARE OF WHERE CHUTE WAS AND WHEN HE STEPPED ON PLUGGED MATERIAL , HIS WEIGHT CAUSED MATERIAL TO FLOW AND LEFT LEG WENT DOWN CHUTE AND RIGHT LEG REMAINED ON TOP.