Congratulations!
As for the Onan, that may be your moneypit for a while. It's probably the carb. They like to be run every month (under load), moreso with ethanol. If you've got an Onan dealer nearby, they'll install a new carb for about $700. Nobody rebuilds things anymore. It's a simple job, but a PITA and one of those things I'd just rather pay to have done. Done once and done right! While they're in there, I'd have them replace the fuel pump (you might as well start fresh). Other than that, the only weak link to the GenSet that I've been warned about is the rubber line from the RV's fuel tank to the Genny. They usually run above the fuel tank, can crack with age and start sucking air. Unfortunately, dropping the tank is usually necessary. BTW, there's usually a shutoff that kills fuel to the Generator when your gas tank gets below 1/4 full. Keeps you from being stranded out in the boonies.
Getting one with newer tires is a bonus - Lucky you! But check to make sure they replaced them with the factory spec original size. A lot of folks are going with the newer metric sizes and if your specs call for a 8R19.5, newer metrics MIGHT be too close on your duals and rub under load. The shotgun blast you hear, could be the resulting blowout. Happened to me twice.
And finally, get a roadside assistance plan from either GoodSam or Coachnet. It's cheap insurance for peace-of-mind and could save you and the Mrs. a lot of heartache.
I hope you enjoy yours as much as we do ours!
