Okay, I'm not that familiar with the model, but if it has a clutch and you're not using it to engage the PTO at low RPM and slowly, you're going to grind.
On my tractor, the clutch is necessary. Start out at low RPM, move the PTO lever into place, slowly release the clutch and then up the RPM.
I know that some JD's don't have the clutch, but a lot do. John