First, welcome to OCC.
In looking at the 782D Wiring Diagram, this has to happen before the engine will roll over.
* The Circuit Breaker has to be engaged (not open).
* The PTO Switch has to be in the "Off" position.
* The Brake Pedal (Neutral) Switch has to be depressed.
* Starter Solenoid has to be functional.
* All wiring in this circuit has to be in good and functional condition.
All of these switches, components, and circuits have to be satisfied before the starter solenoid engages to roll the engine over.
This circuit can be traced down if you have a VOM or DVM meter.
Check the above the best you can and advise.