Power off your John Deere 210 mower and wait several minutes for the engine to cool down before operating on it.
Pop open the John Deere's front engine hood to reveal the engine. Locate the 210 mower's flywheel on the top of the Kohler engine. This circular iron piece has a cover that must first be removed. Loosen and pull out the bolts securing the flywheel cover using a socket wrench, then pry the cover off.
Use a flywheel pulley to remove the flywheel to access the top of the PTO clutch shaft. Move the pulley over the John Deere 210 mower's flywheel so that the pulley's arms reach down over the flywheel's sides. Tighten the pulley's center bolts with the socket wrench until the pressure that is created causes the flywheel to come free from the Kohler engine.
Remove the John Deere 210 mower's oil pan to gain access to the bottom of the Kohler's PTO clutch shaft. Remove the bolts holding the oil pan to the engine using the socket wrench, then pull the pan off.
Remove the bolts along the clutch shaft now that the removal of the oil pan and flywheel have yielded access to the shaft. Use your socket wrench to remove these bolts, as well.
Use a rubber mallet to remove the clutch shaft entirely from the John Deere 210 mower's engine. Strike the top of the shaft just below where you removed the flywheel previously. Multiple strikes may be necessary to pop the shaft free.