My Jem has a very noticeable difference in volume between pickups. The two humbuckers (Dimarzio Gravity Storm) are super loud, but in position 3 the single coil (Dimarzio Evolution) is much more quiet. It's a big difference, and it doesn't allow to switch from humbuckers to single coil on the same song as the volume change is significant. Volume in positions 2 and 4 is intermediate, in between the humbucker and the single coil. Is this normal in Jems?