I decided it was time to perform maintenance on my Onan and went out and got fuel filter, oil filter, and air filter, as well as oil and even radiator coolant. I also went to Youtube and watched a video on how to do it all when I came across an item I had never worked on before. I found out there is a "spark arrestor" mounted into the exhaust system that has to be cleaned. It is located up inside the genny and you need an 11/16" socket mounted on a very long extension. The procedure is to unscrew the 11/16" "plug" which allows soot to come out. Then you fire up the genny and run it under a heavy load like the A/C and microwave for a few minutes. Then you screw the plug back in and the cleaning is done. Since this is my first time working on the genny, I have not done this before and not sure other facilities have done it either. I also don't know what the down side is to not cleaning this item. Anyway, it is now done and no knuckles busted.
As an aside, the last time my genny was serviced, was at Cummins Atlantic in Charleston SC. There is a metal plate which covers the air cleaner filter and apparently Cummins Atlantic decided to leave the cover on the old air cleaner element and not install it onto the new one. I had to buy a new one for about $18. The net effect of this was to allow a whole lot of dirty air to enter into the open top of the filter. I am not happy about this!