I have a vbm jnr as well and I was having all sorts of problems until I followed KKs technique in this thread.
I now produce smooth microfoam every time. Basically start with 90 degrees in the middle and just below the surface ( a few mm) and when the temp reaches about 40 move it to the side but keep the tip at about the same level. Youll be amazed at the results.
Its that simple.