When a John Deere tractor has not been moved in a while, the clutch disk will stick to the pressure plate. While you can can unstick the clutch disk by dismantling the engine, it will take many hours to dissemble and reassemble the engine. A trick is available that will unstick the clutch disk without the having to take the engine apart.
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Connect a chain to the tractor's draw bar.
Connect the other end of the chain around a tree or something that will not move.
Drive the tractor slowly away from the tree. As the chain pulls tight, the clutch disk is knocked free.