Try the actual on/off itself.
Are you sure it's leaking down the barrel or does it just sound like it?
How bad?
There is an o-ring on the on/off which if it leaks, will allow air into the grip frame area, which could sound like it's coming down the barrel if you stick your ear on it.
Take the grip frame off CAREFULLY due to the eye wires and you will see the back of the on/off. Pretty sure there is a grub screw holding it in.
http://www.dyematrix.com/manuals/DM5_Manual.pdf
On/Off is on page 13 dude.
Are you sure it's leaking down the barrel or does it just sound like it?
How bad?
There is an o-ring on the on/off which if it leaks, will allow air into the grip frame area, which could sound like it's coming down the barrel if you stick your ear on it.
Take the grip frame off CAREFULLY due to the eye wires and you will see the back of the on/off. Pretty sure there is a grub screw holding it in.
http://www.dyematrix.com/manuals/DM5_Manual.pdf
On/Off is on page 13 dude.