Something happened and my Onan DJE generator does not run.
Specifically, it starts, but as soon as I release the starter, it
stops. (I test it at least once a month).

An investigation showed that there is no voltage at a terminal to the
holding coil of the fuel shutoff solenoid (this terminal is supplied
through the NC OFF switch and safety relays to make sure that the
generator can be turned off manually or if safety conditions are
violated).

If I connect this terminal to +12VDC, the generator happily runs, but
this is obviously wrong as it bypasses safeties and the off switch.

When I opened the control box, I found a lot of stuff suggesting that
it became a rodent nest. It was completely completely full of
"bedding". I had to vacuum it all out.

So, at this point I will have to find the wire that they damaged and
replace it.

What I want to hear is how can I prevent them from setting home in the
generator again.

i