I had a 2010 Sunseeker Class C. It was the only RV that I have ownwd with zero warranty returns. I didn't have any issues with it. I know Winnebago is a good company but I have no first hand experience with them.
Most likely dirty. Check heating tube for nest of some kind. I have a wire long enough to push through the tube and a rag tied to the end to pull through. Your air mixer may have moved also. At the front of the unit you will see a moveable part that is heald in place by a set screw. Light the heater and move the part to adjust the amount of air that mixes with the gas. You will see and hear the correct location. Your owners manual may have better instructions particular to your unit.
Ebay and national websites most likely will not be a good choice because the tires most likely are not worth what it would cost to ship them. Most likely you are selling them because they are old but still have good tread. You do not have any information on your profile about what type of RV they came off of. If they are a tire that could be used by a trucking company you may be able to sell them to a operator of a small dump truck company to use on their tag axle. Most of the large trucking companies don't have the time or want the liability of dealing with used tires. Put them on CL for a reasonable price and they will sell quickly but don't expect to get much.
I always tell people who are camping at Disney to take DVD's. Disney does have cable. The channels are- The Disney Channel, Disney Channel, This is Disney, All about Disney, Wonderful Disney, Things to do at Disney, Mickey's Channel............
I am starting to see C's on the F chassis (pick-up). Thor has the F-550 Super C with the diesel. I am thinking Ford will continue to dominate the market with the cut-a-way for RV and box trucks. As long as there is a demand they will continue to produce until a better design comes along. I can't see them dropping the line without having a replacement.
I got to thinking about something (scary at times)
I assume to took both of your original dead batteries to turn in when you bought the new ones. Didn't anyone there look at the old and the new and see that they were different?
It is better that you hook up t 6 volt batteries when you needed 12 volt then if you had hooked up 2 12 volt batteries when you needed 6 volt. The 6 volts whould have worked if you had wired them in series but in the long run you are better off with the 12 volt.
I am going to add one to mine also. I didn't realize mine was gas only until the purchase was complete. I got the typical "it will void the warranty" but from what I have found it is cheaper and easier to just fix my RV when something broke. The dealer and manufacturer told me that they cannot put the gas/electric heater in my RV because it is a 30 amp unit. MY class C was a 30 amp service and it had a gas/electric water heater.
From what I can see there is a 110 15 amp plug on the Hot Rod. I am thinking I will just run it on a heavy cord from the campground podium. If I need water heater service it can be easily removed.