An employee was repairing the hydraulics on a track loader and was checking for hydraulic leaks. The cab was removed from the machine for the repairs, but the hydraulic controls (joystick) were still mounted to the superstructure of the machine, which was sitting on jack stands. As the blade pushed down and raised the machine up off the jack stands, the jack stands kicked out. The employee climbed onto the equipment's mounted steps to reach for the joystick to stop the movement and was knocked into an open compartment door, striking his lower chest and abdomen.