Tesla just came out to fix my Model S windshield wipers — they had stopped retracting to the fully closed position. The results are interesting and something that new owners should watch for. Background: The wipers exert considerable downward pressure on the windshield. (Owners, go out and try to left them). That results in good wiping efficiency, but apparently, it can be problematic when they wipe a dry windshield or a windshield with a little tree sap or other gunky material on it. Note also that the autowipe feature is very sensitive, and a simple leaf can cause a wipe of a dry windshield. The Problem (hypothesized by the TM tech and me): It looks like my autowipe activated when just a few rain drops were on a windshield that may have had a little tree sap on it (I know, don't park under a tree ). The extra friction caused by the sap may have caused the wiper motor axle to slip on a conical gear and cam assembly that drives the wiper blades, and as a consequence, the wiper arm end point was changed. The solution: The TM tech got under the hood removed the wipers, readjusted the assembly so that the wipers zeroed out, and then replaced them. Fixed. Ideally, there should be a way to set the sensitivity of autowipe so that dry wipes don't happen frequently. In my case, at least, it looks like the sliding friction of a dry windshield and a little tree sap caused the wiper to slip on the drive axle.