happened on my 19 levos the air shocks would start to knock got a gen 3 Levo comp and that has started to do it now so have been running coil last 2 years on the 19s not a problem had a KSL for 3 months with the same shock as the gen 3 Levo did have one single problem with it just hated the motor that why I sold it otherwise I would of kept it