If you are losing pressure its time to go through the whole system and find the leak. Most of the time it will be the linkage from the servo through the control valve. If the wire binds on the valve and puts a side load on it it will leak or if it is pushing it too far either way it will leak. Make sure all of the hoses are pushed all of the way on the nipples and that the schraeder valve is tight. Use a couple of drops of Marvel air tool oil in the system to make sure it is lubricated. Hope this helps. Don