Elecraft recently released an upgraded ball bearing VFO for the KX3. While all new radios come with the upgrade, older radios can be upgraded easily for just the price of the encoder. After performing the upgrade, I can definitely say that the new VFO is super smooth compared to the original. Here is the video of the procedure:
Elecraft KX3 Ball Bearing VFO Encoder Upgrade - YouTube
Elecraft KX3 Ball Bearing VFO Encoder Upgrade - YouTube