I have a 2007 Kubota MX5000 which turns over and starts fine cold. Once at operating temperatures, if I turn it off, it will not re-start. It won't turn over, nothing. I checked all safety switches, let it stand for 10 minutes, put gear selector and range selector in neutral and it starts. I have re-started it in gear, clutch depressed and range selector in neutral. I have re-started it with everything in neutral and with me off the tractor. This has happened the last three times that I used the tractor. The last time I pulled what I think is a relay plug in on the starter wire and it started. Any advice? Thank you in advance, Frank.