To replace the PTO clutch on a JOHN DEERe Z245, first disconnect the battery to ensure safety. Remove the mower deck by detaching the necessary bolts and brackets, then access the clutch by removing the belt from the clutch pulley. Unbolt the old clutch from the engine and disconnect the wiring harness. Install the new PTO clutch by reversing the steps, ensuring all connections are secure before reassembling the mower deck and reconnecting the battery.