My Levetta was supplied with a 2 hole VBM tip, and it took a bit of getting used to.
The main thing to remember with the Levetta is to place the tip as near vertical as you can, just under the surface of the milk and set up that ch ch ch ch sounding action gradually increasing the steam pressure, until 20-30 degrees Celsius, depending on how much microfroth you require, then drop the tip, ie raise the jug, till the whole of the tip fitting is below the surface of the milk, then texture till the desired temperature.
Rather than setting up a swirling action with the milk going around the jug, it is much more effective with the VBM to have the milk tumbling over itself! Much better microfoam results...trust me on that!
I would not recommend blocking any hole in the tip.