Cub Cadet Rzt 50 Pto Switch Test . Mowed for an hour yesterday after installing new starter key switch and pto cut off by itself. The pto, which controls the mowing blade, must be in the disengaged, or off. Blade Clutch PTO Switch replaces Cub Cadet 2012 from blades.zeroturnmower.info It stops the mower from starting involuntarily. A new electric clutch ($250) is the answer. Two weeks ago it would no longer engage the pto.