I know nothing about Agco's asI never see them
But with a mower of that age, considering the use it will be getting the only thing I wold worry about is the hydro
So quick & nasty check is to try and push the mower , brake & engine off but bypass in the run position.
A good hydro will be very hard to push a stuffed one will be easy to push.
I do my assesment on my tilting trailer
If it stays there when I tilt the trailer ( around a 30 deg slope ) then the hydros are good
If I have to push hard and it stops the instant I stop pushing it is excellent
If it pushes easy but still stops then I stop it is OK
If it starts rolling and runs off the trailer with no further effort then it requires service
If it runs away the instant the brake is released it needs replacing.
Now most times the mower is actually driving when I take it for a service so they have not totally failed yet .
agco being a beter brand probably use a servicable hydro and if it were me, I would be replacing the oil & filters just so I know when they were done .