My Exmark #255504 , lz52kc23hp, is having a problem . when I engage the PTO the whole engines shuts down. So far I have switched the PTO 3 times, checked and cleaned the entire wire harness, changed both of the relays, checked both fuses, and even made sure the fuel filter was not dirty. The motor begins to turn the blades but it is like it just gives up. there are no blade or spindle obstructions and I am out of ideas. can anyone help me?