Stormin Mormon wrote, on Fri, 12 Dec 2014 08:44:03 -0500:

1) Start with the basics. Change the oil, make sure
the unit is clean and free of dust and debris.

I've never changed the oil, but I doubt that's the problem,
but it's a great idea nonetheless. I'll also take the
battery down to Autozone to have load tested.

It had 536.something hours on the clock when I snapped
that picture of the front panel in the night. I'll look
when it gets light to see how many hours it ran last
night.

2) Look for online forums. And read any paper work
you have with the machine. Might be able to get
the manual from the web site in pdf.

Googling for "Generac model 09067-9 series 8KW HSB"
I didn't find the manual, so, I'm calling them as we type:
http://www.generac.com/service-support 888-436-3722