An employee was observing the installation of a boom mower which was being moved by a forklift. When the load was relieved from the forklift on the left side, the assembly shifted toward the forklift and out of alignment with the tractor. The forklift operator attempted to reposition the load balance; however, the load shifted forward and the right side of the assembly dropped off the forks to the ground, striking the employee's right foot. The right foot was crushed and the tibia, fibula, and heel bone were broken.