If this is the reg you are using then the following will apply.
If the tank is empty, the output pressure will always register as 'Lo-P'
The output pressure adjustment screw is located on the front face of the reg (in the centre of the circle).
Screwing this ANTI-clockwise (out of the reg) until it is loose will cut off the air output and if the tank is full or empty it will register as 'Lo-P'.
If the reg and tank is not connected to the gun, and the screw is far enough out so that it's very loose (practically all the way out), you can fill the tank without worrying about the air escaping from where you attatch the hose.
Once securely connected with the marker, hosing in place and tank full. You can begin to screw the output pressure adjustment screw CLOCKwise into the reg. This will slowly increase the output pressure and you will hear it when it first starts allowing air to flow into the marker.
You may have to fire off one or two shots from the marker to stop leaking inititally. Depending on the marker it may leak until you wind the pressure up high enough to seal it.
You can monitor the output pressure on the LCD screen as you turn the screw. It can become physically difficult to simply wind the screw straight from 0 up to 750-800 psi (especially with it being such a thin allen key, so fire blank shots as you continue to screw it in to help equalise the presssure, this will make it easier.
From then on just use the LCD to monitor the output pressure etc. If you need to lower it, screw it out a bit. Increase it, screw it in a bit more. Away you go!
Good luck.
Also - An official full manual can probably be found at www.wdp.tv
