Mathey,
At first mine only made the noise while pushing the hydro, and I could get it to move a little. I had to get it to move to get it back to the trailer. I got it to move about 10 foot and then that was it. I had to move it with the loader and get it on the trailer with the loader as well. Once it would not move any more it made the noise as soon as I started the tractor. At first I thought that I had hit the lever and popped it out of range, further investigation told me that everything was in order and that I had something wrong inside.
I hope that my problem is not what you have, but it sure sounds to be the exact same.
I had about 200 hours on mine when it did it. I hope that as we see CK 20's get more hours on them we do not see more incidences of this happening. I know that there are members here with high hours on their CK 20s, but we have 4 of them, and if it happens with another one of ours, I will not consider it a coincidence. My confidence was shaken when this happened to mine, now it sounds like it happened to you. I hope that these 2 are just a couple of flukes.