I have a 2017 Model S and for a year or so I have noticed the ride has become quite hard. It is particularly bad at low speeds on bumpy surfaces and i get some rocking from side to side. I've taken it in to Tesla twice. The first time they said it was OK but replaced a part (ground bracket?). The second time they replaced the front near side air suspension unit. This made things a bit better but it's still not right. I don't think I've got a leak as the car doesn't "sag" when parked for a while. It's all very mystifying. Does anyone have any ideas what it might be?