An employee was contracted to perform work at another facility to relocate a molding machine. Normal procedure is to bring the machine within about one inch of the leveling pad so that a bolt can be hand placed to align with the hole on the machine that is being bolted down (to conclude the relocation of the machine). While using a hydraulic jack to perform this task, the hydraulic jack "failed" as the machine came down on the employee's left hand crushing it in 3-4 separate places.