I just bought a new Mark IV - I absolutely love it, but I have one problem and I wonder if it is normal for all Mark IV's. My master volume does not allow ANY signal between 0-1. Then when I get to 1, it suddenly jumps to what I would call 3 on a Fender Twin. Then it is up to 5 on a Fender Twin by the time it gets to 1.4. So I have all my usable practicing volume control in the region between 1.0 - 1.4, which makes it very difficult to adjust volume - one must have an extremely steady hand and a lot of patience to try to "tapping" the knob to the desired volume. Are all Mark IV's like that?