not necessary to get a replacement, you can adjust the needle stem, to lower the minimum flow control range.
but don't over do it, this metering valve is not a shut off valve, you can't use it to cut off the flow completely.
up the output pressure on the regulator to 50 psi, and follow the steps below, adjust the position of the needle stem until you still have really slow bubbles coming out of the outlet is good enough, to avoid damaging the needle stem.
----The Parker M series has a manufacture preset lower flow control threshold that might be a little bit high for our application, so sometimes need to adjust the needle position to lower the flow rate.
first, gently tighten/close the valve handle,
second, use an allen key to turn loose the retaining screw on the handle, pull out the handle (very) slightly, then tighten the retaining screw.
Now you can turn close the metering valve handle a little bit more--the needle stem goes into the orifice a little further, less gap between the orifice and the needle.
repeat above steps if the valve at close position(lower handle stop/touch at the valve shoulder) but the bubbles goes through still too high.
do not turn the valve to close with force, and if you adjust until the lower handle not touching the valve shoulder but stop, it is the needle inside stop at the orifice, excess force to turn it close even more will damage the needle.