When pushing down the edges of the top plate diagonally, the appliance should not move up and down at all (check both directions).
If the appliance rocks when pushing the top plate of the appliance diagonally, adjust the feet again.
Check whether the appliance is perfectly level after installation.
Timber or suspended type flooring may contribute to excessive vibration and unbalance. Reinforcement or bracing of the timber floor may need to be considered to stop or reduce excessive noise and vibration.
Never try to level any uneven floor by putting pieces of wood, cardboard or similar materials under the appliance.