2003 Rear Power Window Motor

The right rear power window on my 2003 Windstar stopped working. When I press the button I can hear a click, but the window doesn't move. Is the motor bad? Where can I buy a new one? How easy is it to replace myself? It looks like I need to remove one screw and the seat belt holder to get at the motor. I don't have the right tool to remove the seat belt holder, where can I by one?

Thanks in advance for your replies.