Originally Posted by parapaul
The wiper arm moves freely with the glass section raised, and strangely also moves freely with the glass down and wiper switched on, almost although the motor isn't powerful enough to move it.
With the glass door up, you should see a round disc with a hole in on top of the main boot cill.
This is the rotating disc that moves the wiper (as the motor is in the tailgate not the glass obviously), there's a peg on the back of the wiper arm that should go into the hole in the disc when you shut the glass.
If your wiper arm is moving freely with the glass shut then one of 2 things has happened:
1. The wiper arm peg is not locating in the disc hole (most likely)
2. The disc has broken free of the drive motor and is just freely moving
Can you hear the motor whirring when you try to operate the wiper electrically?
Look and see where the disc hole is, then see if the wiper peg (with wiper in rest, 9 o'clock, position, is in the same place.
Let us know..