A new generator is going to cost a lot and you will find as you go along that it is very well worth having. The genny is supposed to be run every month for at minimum 45 minutes to two hours (2 hours per Onan) so this is way under maintained. If the genny is low on oil it will shut off. If the RT has less than a 1/4 tank of gas the genny will shut off. But I would want to see it start and run for at least an hour before I gave it the OK.
If the air bag light is lit there is something wrong and this should be fixed by whoever is selling it - or get an estimate for the worst case repair cost and have that deducted from the price.
Sometimes you just have to let one go that there are doubts about and move on to the next one that you find. Too many buy and figure they are going to fix what comes along and wind up investing many thousands more - there is one guy who has hit $10,000 in post purchase repairs and his still needs repair. Don't put your money in a money pit!
Plus what has been checked in the coach - electric system, plumbing, propane system, appliances, and more. You want an RV service center that knows Roadtreks to go over this coach top to bottom.
