Bart,
I have a 6' kk finish mower, and it is very hard to turn the pto shaft by hand. My 5' brush hog is fairly easy to turn. I believe the difference is due to the pullys and the tension of the belt. Since my NH 35D pto shaft does not freely turn, I am forced to turn the shaft on the implement when connecting to the tractor. As I said, this is a bit difficult with my mower, but since I operate the mower without the belt guard in place, I am able to turn the shaft by pulling on the belt, which rotates the shaft. It's a bit awkward to do while trying to hold the shaft collar to the tractor pto shaft, but it works. Hope this helps. Good luck.