EMPLOYEE WAS ON 3RD OR 4TH STEP OF AN ""A-FRAME"" STEP LADDER, INSPECTING THE BEARING AT THE FEED END OF A SEPARATOR SCREW. AS HE STARTED DOWN THE LADDER HIS LEFT SLEEVE STUCK ON SOMETHING. AS H E TURNED TO FREE HIS SLEEVE, THE LADDER SLIPPED AND HE FELL 3 TO 4 FEET ONTO LADDER.