Hello, I have a commercial zero turn that will not shut down if I'm off the seat and the brake is off. Will not shut off if the brake is on and I try to drive forward. Will not shut off if I get off the seat and the blades are ingaged. I checked all the switches (parking brake, both drive levers, and seat switch, and they seem to be working just fine, so I could use a hand in diagnosing what is up with this unit. Also I could not find any safety switch that is activated by the electric PTO, so I was wondering how the unit determines that blades are engaged. Thanks for any help.