Btw Al, Mystere doesn’t have regular rotary pot volume but resister ladder control, if that matters.
Photos of the amp appear to show that the minimum position of the control is around 6:30 or 7 o’clock or so, and the max position is around 5 or 5:30 o’clock or so. And of course the control is rotated between those positions, as opposed, for example, to a control that is rotatable through multiple turns (with a separate indication of the volume setting being provided), or a control that consists of an up button and a down button. Given that, whether the control is a continuous pot or a stepped resistor ladder makes no difference with respect to what I said earlier.
Good luck. Regards,
-- Al