Need help/advice o JD 4200 W mid-mount mower not responding

[rickmyers]

I have a JD 4200 with a 72" mid mount mower. The mower does not respond to the tractor's lift / lower commands. Probably a hydraulic cylinder. Any idea how hard to repair / replace myself? When it does respond, it's not level. Left side won't come up at all, and right side sometimes moves, but stays high. Thanx