On the side where the ball is missing, assuming the lug/ear end of the frame into which the ball screws is intact, you can just replace the ball pin. It screws into the end of the top frame and you can then tighten it by means of the thin hexagon shaped base (13 or 14 mm, IIRC). It might be a good idea to re-install that ball with some red loctite as a loosened ball often causes the lug/ear end of the top frame to break off ( a new bow for that part of the convertible top frame is almost $3,000 at the dealer).
That particular ball pin does not seem to have a Porsche Part Number, although another ball pin in that area (on one end of the V-lever, where one end of the black "hydraulic" pushrods is pressed onto it) may be the same part number, and that part number is 986.561.689.00. Compare that pin on the end of the V-lever with the one that screws into the end of the top frame (the one that is still on your other side) and if it's the same, you can order it with that same part number.
The fix for your overtightened clamshell depends on which version of the convertible top transmission your car has installed.
Regards, Maurice.