Do not know the answer, but here is what I would check. Did you clean the pickup screen/mesh filter? If not you need to do that. If you did, when you put it back in did you put it in the correct direction? Did you use John Deere hydraulic fluid? Do you have steering?
I have included a picture of the hydraulic system.
You need to clean the pickup screen. It is located back by the PTO shaft. I have included pages from the owners manual to show its location and how to clean it. The issue at this point is that you will need to drain or siphon some of fluid out first. I have heard people put it in backwards, so remember how you took it out. I do not know how much that would be.
On the fluid the screen is 125 mesh and have read some non John Deere fluid have a hard time going through it. See what happens when you clean the screen using the fluid you purchased.
Something you may find of value. When replacing the fuel filter add the following steps to what is in the manual. Fill the tank and fill the fuel filter before putting on. This is what I do and I have never had to bleed it, before starting it.