[Awaino]

Going through the list of items to replace/work on and I got to the rear wiper which has not been working since I got the car. I turn the wiper on and it goes over to the right and stops. I thought maybe my motor was not working and so I had the cover off and had my wife working the switch. The motor is fine, it just seems to lose the connection to the wiper arm when it goes over, and then doesn't bring it back. Have any of you seen this? I'm wondering if my hatch is not closed all the way or something that would cause this. Some sort of misalignment maybe, or tired springs in the mechanism? Any ideas would be appreciated. Thanks.