Power Door Locks: 2000 Focus Se Wagon

My PDL system motors sound weak and slow when operated. The F63 (20A) fuse on back of the fuse panel that controls this curcuit keeps blowing when I try to use it. The wires seem ok and the switch seems OK, but its hard to get to the motor to check those. The wiring diagrams in Hanes suck to be quite frank. Any ideas??? Jeff OHIO