Just purchased a very clean 455 with less than 200 actual hours. The unit on occasion will not start. The fuel shut off solenoid is the issue. It engages the fuel shutoff then releases it and shuts off fuel with the key in the start position. Replaced the solenoid, this did not correct issue. I am now thinking it could be safety switch under seat, on the brake pedal or even key switch and the board it is attached to that controls glow plugs and fuel shutoff solenoid. Any thoughts would be appreciated.