Do you know where the vibration is coming from? Could it be vibrating in the tank? Or can you hear it well and feel it on cartop? Might sound dumb but we had a similar problem, noise was coming from the tank. Drained the tank, cleaned the pump and realized the rubber hose for the return out of the valve was hard against the pump. We cut it and the noise went away 🤷🏻♂️
