PULLING A 4 YD MUCKER FROM A SUMP USING ANOTHER MUCKER. THERE WAS AN OPERATOR IN EACH MUCKER. THE MECHANIC WAS ON TOP OF DEAD MUCKER WITH A PORTAPOWER TO RELEASE BRAKES. THE OPERATOR OF THE ST UCK MUCKER GOT IT STARTED AS IT CAME OUT OF THE SUMP & PULL AHEAD CAUSING IT TO BREAK LOOSE FROM OTHER MUCKER. THUS CREATING A DROP THAT CAUSED EE TO FALL SPRAINING RIGHT KNEE.