I've had these on for almost 30k miles (16k miles for one that was replaced due to an accident) and I am wondering when I should get them rebuilt? I've developed some light rattling at <10mph over bumps and overall, they dont feel as firmly cushy (if that makes sense). I mainly DD the car and **** around take turns as hard as the car will allow sometimes. Are rebuilds part of KW's lifetime warranty? If not, how much do they charge for the rebuild?