Since you are very knowledgeable on Smart 451 ED I have a simple question regarding a "Thumping noise" I hear only when on power or regen. It seems Torque sensitive not speed related. Not motor mounts, not CV axles and I have replaced the motor too due to it sounding like a bad bearing or rotor rubbing the stator... The noise is still there. I also changed the gear oil and saw absolutely no metal particles. Can the VFD Drive unit make a thumping noise? Maybe something came loose inside?