There are a couple of things I noticed in the schematics and your description of the setup. By way of schematic the convertible appears to have a Normally open unloading valve (item 9 & item 11). This solenoid would need to be energized when any function is going to being used. This unloader valve shows that when it is energized it checks or blocks flow from port A to port B and allows flow from port B to port A, therefor the oil supply from your machine to the converter valve must supply to the A port and the B port must connect to tank. The schematic may be incorrect because the the 4 pilot valves in the convertible manifold shows that if the unloader valve was instead blocking between A & B ports when energized then the valve could be supplied oil on either A port or B port which makes more sense to the design of the manifold assembly. The Trigger would therefor be operating the 4 way 2 position valve when you needed to change direction of any of the cylinders. Not sure why they made it so complicated for what it is but I think it may be they way they wanted to have a multi directional oil supply on A or B port which is a handy feature and eliminates the need for a reverse flow check valve. Best regards