Canadarm can't even move itself -- on earth
The Canadarm can move some heavy stuff in space, but it can't even move itself on earth.
"Meant for a weightless environment, Canadarm cannot even lift itself off the ground in Earth's gravity. A special test room was built to allow the arm to flex its joints under operating conditions. In addition, a computer-based simulation facility, much like a video game, was built to evaluate controllability and provide training for astronauts."