are they just not holding the windstop at high speed? if so take some black electrical tape and trim to size and wrap around the nubs on the wind stop. been working for about 2 years now.
There is a kit that Porsche sells to replace broken clips complete with pop rivits. The part no. is 986.561.323.00. The individual clip part no's. are 986.561.737.00.01C (left) and 986.561.738.00.01C (right).