I have a case international 275 with a live PTO and a 2 stage clutch it has always been hard to disengage the drive wheels. the drive wheels are supposed to stop when you push the clutch down 1/2 way and the pto disengages when the clutch is all the way down.this does not always work and you have to push the clutch to the bottom to disengage the wheels. I think that the problem may be in a hydraulic valve but i am not sure. Any thoughts?