Case Super N hyd. trouble

We have a Super N with 1000 hrs. It has had trouble since it was new, and back to dealer 2 times with no help. Warranty is now out, and has been back to shop again for this continuing problem and still no improvement. The front bucket will roll up when supporting machine while digging with backhoe, the boom will creep to side, and bucket dipper cylender will creep off rapidly, and has low power on all functions. Any ideas as to what to look for.
Any help will be appreciated.
Thanks

Case Super N hyd. trouble