check the stickies at the top for a diagram on common leaks.
leaks by the solenoid are usually the bolt sail, or outer can orings.
i would replace those first...bolt sail first. then the outer can ones.
if you stilll have a leak, i would pull out the on/off and look at those orings.. replace em, then dont touch the on/off ... i never liked things on the dye guns. never used it anyways...
its usually something simple, but sometimes time consuming to find.
hope you get it worked out.
my m2 leaks....