I have lost the intermittent and low speed on my wipers. This occurred earlier on my '92 968 and I was able to fix it. I began by replacing the switch but that did not provide a cure. I'm approaching my 88th birthday and find I can't remember some of the fixes I've made on this car, but I believe this fix involved removing the wiper arms so I could remove the plastic piece that shields the wiper motor, etc., and then finding a bad wiring connection. It has been my practice to enter information on repairs I make on my cars in a book, recording the date, mileage, etc. But I didn't do it on this repair. Might add that I have a '60 BN7 Austin Healey, and the number of wiring, etc., issues on that car has been pretty large. The two higher speeds on the Porsche still function. However, I'm in Florida and deal with a lot of moisture on the car's windows in the morning, making the intermittent wiper function particularly useful.