JM 304 TPH Question

Hey guys, I have an issue with my TPH that I'd like some guidance on.  My 2007 304 Jinma has the single-lever control for the lifter; top half of the movement is position control and lower half is draft control.  That's all well and fine, I understand the difference and applications thereof, but the position control is a bit too arbitrary to suit me.  If I have the bush hog on and raise the hitch up I have to pull the lever nearly to the top of the travel to get it to initiate movement, then it goes right up.  When I want to lower it to cut, I have to drop the lever nearly to the bottom (of the position control portion) before it even starts to drop, at which time it goes down pretty much all the way.  I can finesse it into the position I want by going back and forth until I get lucky, but that isn't really too handy, you know?  I'd like it to be more “linear” in action (more determinate, so to speak), so that when I move the handle a little bit I get a little bit of TPH movement – in a predictable way.  Not this random chance routine I have to use at present.

So, what's the answer?  Do I simply need to adjust something, or have I somehow along the way screwed the pooch and need to rebuild the lift cylinder?  I'm thinking the cylinder itself is okay since it stays up when it's supposed to, even when I'm bouncing all over on rough trails.  Is there something that needs to be done to the control valve for the TPH? 

I'd like some direction before I just blunder into this since I'm not a wizard with hydraulics – I understand the theory, it's the practice I fall down at.   In theory, there's no difference between theory and practice – in practice however, there is. 

I await enlightenment! 

Rich