Spoiler wall failure
The Porsche 964/993 back spoiler mechanism is equipped with a plastic rear wall that is supposed to fold up into the engine lid when the spoiler is down. The plastic is known to crack and tear, especially along the folding recessions. According to Porsche, the wall is important to allow correct air flow and cooling of the engine.
It is a 10-15 minute job to change the spoiler wall, and it can be done without disassembling anything by the wall itself and the rubber seal connected to it. First, open the spoiler by pressing the knob inside the car, and open the engine lid. Disconnect the rubber gasket at the lower end of the spoiler. This gasket has several sections between the grille sections. Use a flat screwdriver or similar to drive the spoiler snap lock all along on the top end.
Unlock the snaplock at the bottom end, this is the square section that snaps on to the metal cross rod. This can be a bit tricky due to the rod bending a bit, but work your way along the rod with a screwdriver. Disassemble the sectioned rubber gasket from the failed spoiler wall and reinsert it in the new part.
Install the new wall
Grease the cross rod, greatly simplifying the reassembly. Grease the according square snap lock section on the plastic wall. Also, grease the top end snap lock to ease reinsertion. Reinsert the square snap lock along the cross rod. This may need some force, but it is quite sufficient to use your thumb to press it in if the parts are greased. The metal cross rod also may bend a bit on the middle. Make sure the wall is forced over the lock knob on both sides.
Reconnect the gasket to the grille assembly, it might need some sideways adjustment to fit into the grille openings.
Use a long flat screwdriver to drive the top snap lock into place. There is a catch on the other side of the wall that is perfect seating for the screwdriver.