Pressure pushes the shaft out unless you hold it in. Whether that's a problem will be up to the user....
With the assembly pressurized, turn the knob whilst advancing the shaft towards the
orifice in order to line up and engage the slotted or hex side with the orifice. Make
the necessary adjustment as per manufacturers recommendations. Note that you
will push and adjust against the pressure, which is a little 'though'. This is perfectly
normal due to the nature of an unbalanced in-line orifice adjuster design. Once you
release the pressure on the knob/shaft assembly, the shaft will disengage from the
orifice and be pushed backwards, This is perfectly normal and inherent to
unbalanced in-line orifice adjustment tools.