Pull the trigger wire off the solenoid and check it for battery voltage with the controls set for starting and the key in the start position.
If you have battery voltage on that wire, then either the ground on the solenoid is bad or the solenoid itself is bad.
If not there then the cranking circuit is not functioning
So one of the switches or the wiring between them is duff.
The link previously posted should have a parts manual download some where
Download it and at the rear is the wiring diagram
From the diagram you will see power to the starting solenoid goes from the B terminal through the brake switch through the PTO switch then to the solenoid