I have had a JD4100, and two JD4520's with the same lift mechanism. Firstly, those aren't the draft arms, they are the mower lift mechanism. So when folks say that the draft arms should not hit the ground, they are correct, but it's not your draft arms that are touching, it's your mower deck lift mechanism. All of my machines did the same, they have to in order to latch into the drive over deck properly. You have two easy solutions to the problem, either use turnbuckles to hole the mechanism up when the deck is not installed, or you can actually buy a chunk of steel from John Deere that us meant to attach to the hole in the frame above the mechanism bellcranks, and also attach to the clevis built into the bellcranks. Ask a dealer a about his part since I don't have the number handy. It's just a piece of flat iron with a hole on each end. The top end is attached to the frame with a bolt, the bottom end is attached to the bellcranks via a pin through the clevis. You can easily make one of these yourself if you have some simple metal working tools.