I had a new 2520 in July 07, it had same problem at around 70 hours also. The loader would only go up 1/2 way and had no down force to dig. Backhoe was just fine. Dealer took it for a month and replaced power steering part by fuel tank, didn't fix probem but I needed tractor, in fact now transmission made noise. Took it back around 120 hours and they had it for 6 weeks and swapping parts per JD support, not fixed so I upgraded to a 3320 in Dec 07. I know they fixed it but, it sat on lot for a while before they sold it.
Note: I had replaced hyd oil just before I took it in. They found LOTs of metal pieces in the filter screen ( I saw them ), but I think a lot of people see that 1st change.