As I stated earlier I have a LP powered 16Kw Generac that was installed over 20years ago. During our last outage the generator shut down and indicated an overspeed condition. I called a couple of service companies who said the best they could do was weeks, not days, to get here.
After some thought and on-line research I was able to diagnose the problem and fix it myself. Turns out the butterfly in one of the venturis had come loose and wedged itself into the venturi after the screws came out. Not that big a deal, since there was no apparent damage to the cylinder despite the screws getting into them.
I did find a couple of other folks who had the same thing happen. My bet is Generac knows they have a problem and all I would expect from them is a notice to owners to check the butterflies to ensure the screws have Loc-tite on them. I did not see any evidence of Loc-tite around the screw holes.
If you have a Generac and want to check it I would use a scope inserted through the intake manifold tube. Or you can disassemble the mixture box to look, but plan on a couple of hours to do it. You can find detailed instructions on how to do it here:
https://gentekpower.com/forums/viewtopic.php?f=6&t=2745