WoBoxster, my friend what you have is a messed up cable....In summary what happened is that one of the cables either snapped or got loose from the housing on the to motor...It is located inside the top cavity at the rear center, you'll see two covered cables running into it from both sides....another consequence from this action is that you may have a snapped guide arm from the same side is less retracted...What happens is when the top gets un-synchronized one of the sides pull more then the other causing more stress in one side and usually that's the side that snaps....Very important to notice if this is the extent of the damage then you are ok...all you need is the cable (you can get it from any porsche recycler like Oklahoma Foreign) and maybe the broken guide, if you can get the plastic cap (some are red) even better....the procedure is rather simple to get it synchronized again...If you need help with this I can give you a step-by-step.
However if one of the sides instead of the plastic cap it's the metal ball where the cap goes that got broken.

..then my friend it's a different ball game. you will need to replace the central bar segment of the side which, for lack of a better word, It's a ******************** to replace (yes you guessed it happed to me too) because it's much more difficult to come accross this part although not impossible....