I have an older DYT 4000 Model # 917272247 and the mower deck will not stop spinning. I replaced the switch up top and did not help. I dropped the deck and even unplugged the pto from the system and it still spins. I am wondering if it spins all the time or should it stop when the switch is disengaged. It just started happening and due to the ruggedness of my property i need to be able to control the blades. Any advice or troubleshooting hints would be greatly appreciated.