At this point reading the history I would drop the generator and take it in for repair. At 270 pounds that might be easier said than done but you'll save some of the labor cost. If you have access to a transmission jack removing it isn't very hard. Any small engine repair place should be able to work on it. It might even be a Briggs and Stratton engine that was rebadged by Cummins. Take it to a true expert with small engines which might not be your local RV service center.
Until you can get the generator operating reliably further effort with the AC's isn't going to be very productive.
