NH 488 cutter bar height

Although I've been using a Haybine for many years,I still have some things to learn.

 

I pull a 9' Model 488 with a Ford 5000 which has 38" rears.Drawbar height is at spec.

 

I'm trying to raise my stubble height without success.I was running with  the skids in the middle slot but moved them down to the forth and now all the way to the fifth and final notch to try and raise the cutter bar height without success.Actually,it might be worse.I also made sure the pin stop was where New Holland said it should be to flatten the cutterbar tilt angle.

 It appears when I lower the cutter bar the skids stop it high enough but then the bar will still tilt farther forward and put a steeper downward angle on the knife.

 Would switching to a single  spool setup on the cylinder help stop the forward tilt and allow some kind of float for the cutter bar or should I attempt some kind of extension to the stop weld assembly.

 Ireally would like to leave about a 4" or more stubble height to help the health of the grass and help keep down the weeds.

 

NH 488 cutter bar height