Exactly the same thing reported by one of our crew chiefs. I take it off the trailer and it starts fine. I don't think there are any relays so it is either the starter switch, the PtO, or the starter. Since mine is under warrant I am replacing the switch and pto first. Our unit is about a year and half old.
I swapped out the battery so that isn't the problem. I guess a goofy interlock but.....guess I ought to look at the brake and gear ship interlocks they could be sitting on the edge.