Rear wiper constantly wiping/randomly wiping

[pbanf]

Hi, I have a Passat B6 2006 estate. The problem (at the moment) is with the rear wiper, I've been googling around for answers but as yet not found anything. So what its doing is wiping as and when it feels like, even with the wiper stalk in rear wiper off position, mostly it is just constantly wiping but sometimes when i feels like it, it intermittently wipes and sometimes randomly stops the arm in different positions on the window.
I guess its down to the motor unit in the rear door (which ive taken apart, dried out (as it was wet inside) and re-greased) and still the problem is happening, but I wonder if any one has any more info on what this problem could be or a work around to stop it constantly wiping? I dont care if it doesn't intermittently wipe but wipes when the washer is triggered.