Well, after more than a year without major problems, this morning I found the car leaning on the rear right side. I think the rear air spring has a leak, but the car only has a visible drop after a few hours. Can I replace the air spring myself? The procedure seems rather simple, except for the suspension depressurisation using the testbook... Is this really necessary? Did anyone change a rear air spring? And, since I don't see any visible damage on the rubber part, could it be another cause for the drop? There is no hiss, and once started, the car raises to normal height in seconds. Thank you!