[greglepore]

Well, actually, they are known to be problamatic. They all fail at some point. The cylinders are available for around $800 exchange, and its 10-16 hrs to diy it. But its not easy-there are microswitches subject to damage, and it can be a giant pain if it doesn't communicate properly with the control module. Also, there are a bunch of e clips that hold stuff together that have a habit of flying off into the bowels of the car.
The good news is that you can operate the top manually-its not easy and not a long term situation, but if caught with an immobile top it can be opened or closed.