Jeff, did you get this figured out? I've had this very issue for a while. I thought I had it figured when I replaced the last relay in the safety switch chain and the problem went away for a while. It popped back up again and this time I'm 95% certain it's the PTO switch. I disconnected the plug on the switch with the two purple wires, jumpered the connector and it started. The 5% uncertainty is that I plugged it back into the switch and it started as well. Could have been just an intermittent connection, but I felt the two prongs on the back of the switch and one was loose so a new switch is on the way.