Not really any parts that require routine maintenance. The Boxster top isn't hydraulic, it's electric. You can check the ball joints that are at the end of the push rods. If the ends are red, they are almost certainly the originals and they have a tendency to get brittle over time and break. Once one breaks it puts twice the force on the other one and it will soon break as well. If they are any color other than red, (white are from Porsche, I have also seen black aftermarket ones), then they have been replaced.
