I got the pictures, but they were unnecessary. You could have just told me the model number.
Unfortunately, if it is running, it is working and can't be fixed. You are going to have to wait until it acts up, and catch it in the act to be able to know what is wrong.
From what you are describing, I have to wonder if you are having a battery issue in the coach.
Start with checking the battery cables/connections. Make sure all connections are clean and tight.
Pay special attention to the ground cable that runs between the genset and the frame of the coach - it is often overlooked, as it does not connect directly to the batteries.
If it has been a while, consider giving the unit a good tune up.
If it happens again, you need to check and see if you are getting battery voltage to the starter solenoid while it will not crank.
If no voltage there, the problem is in the batteries/cables.
If you have voltage there, the problem will be in the genset control.