Hello! I ve got a some technique problems with vibrato on my fretless electric bass. First, I find that there is at least two different techniques to do that thing on the fretless - just check this guy On the first video he just moving his finger around of the fretboard, the second - sliding a little between two notes. On my bass (fender am std fretless) if I doing that as the shown on the first video, I got very weak vibrato. The second way works very well, but here I get a lot more tension in my fretting hand which is not good. So, I totally not understand how to make a nice singing vibrato, I hope somebody can help me with. Instruction with photos will be very helpful.