I find with my 4300 that the PTO is either engaged and locked in gear with the drivetrain or disengaged and locked so it won't move/spin. In between these two positions there is a very small spot in the lever movement where you can actually turn the shaft. I have a small (4') offset rear mount bush hog that I made that needs to be sharpened after every few hours use (the blades are soft and I hit the odd rock beside the trail) This small sweet spot in the lever movement is the only way I can spin the blades by hand to get the grinder to them.
When I had the little "Bota" I could disengage the PTO and it would spin down freely, with the JD it stops abruptly when you try to dis-engage the PTO. A pain when using the brush hog or snow blower. The first time I blew snow I sheared the bolts when I pulled the PTO out of gear at operating RPM and the shaft STOPPED!