I have a 2002 case 621D loader and while in use one day it just stopped. It will start, idle and rev up fine but it has zero hydraulics. No bucket controls, no forward or reverse, and no steering. The filters have all been replaced, the hydraulic oil level is full. When it first starts it will have steering for a split second then nothing. Any ideas?
I would be taking a look at the flexplate area. Not sure if you have the Cummins or Iveco engine as 2002 is the changeover year. Regardless, the convertor is driven by 4 bolts. There is an inspection plate in the bellhousing to access the flexplate bolts, hopefully, by looking behind the plate you will see the issue.
You have a drive coupler that connects your driveshaft to your flywheel make sure that the rubber center has not stripped out. I know this is a late response but I hope it helps.