Scag Turf Tiger 28 hp Caterpillar Diesel, starting issues

I have a Turf Tiger and it fails to start via the key, after you shut it down for a short time.
When I turn the key, it makes a clicking sound like a flat battery solenoid, battery reads 12.7 volts
I have fitted a secondary start switch, from the positive battery terminal to the starter solenoid, so I can move it.

The 12 volt 40 amp solenoid mounted inside the control box also clicks consecutive when trying to start.

I look forwarded to your thoughts!

Regards
Graeme

So it runs when you use your secondary start switch?

If your secondary switch starts the mower, I would say the problem is between the switch and the solenoid. Most likely an OSHA switch is interrupting the voltage from the switch to the solenoid.

First thing I would do is turn the key to start position while simultaneously over working the OSHA switches. Over Work the levers, parking brake, bounce around on the seat, ect. (I started a friends mower Saturday doing this very thing and determined the brake switch was the problem.)

If that did not find the problem, I would get out my test light and follow the current from the switch to see where it is interrupted. A wiring diagram would simplify this process.

I am not a tech and usually repair my own stuff. You asked for our thoughts, well these are mine. Good luck.

You may have 12.7 at the battery but what voltage do you have at the solenoid when trying start