Rear end slipping on John Deere 1010

Hello, I'm found a John Deere 1010 for sale. The owner says when you turn the tractor either using the differential brakes or the steering wheel, the rear end slips a little, and if going slow, the tractor will actually stop for a second, and then starts moving again. Any ideas on what could be causing this? Thanks,

Since the 1010 is a gear drive system either the clutch is slipping or gears. Since there is no associated crunching sound reported I would say clutch. It could be as simple as a free play in the pedal issue or the disk could be shot. Replacing a clutch requires splitting the tractor which requires the right equipment or $$$.