Cayman S - rear window wiper doesn't work

[Largie]

My son has recently bought a very nice Cayman S. The only thing wrong is that the rear wiper doesn't seem to work. The fuse is ok so I guess it falls to the switch, the control system or the motor.

Does anybody have a view as to the most likely? And can anybody advise how to remove the panel on the inside of the tailgate so I can access the motor. It looks as though you just pull it off the clips? but before I try I would like a bit of certainty. I have read somewhere there are two screws, are they behind the tailgate light or behind the fixings for the closure flap.

Any help will be gratefully received.

I guess it is not the end of the world if it doesn't work but...........

David