Francine,
I, too, am on my second National product. Although National is out of business (November 2007), they made one of the better motorhomes on the market. When they are available at one of our local RV sales lots, they do not last long! Many other brands sit on the lot for much longer periods of time.
As also mentioned, have a qualified RV mechanic check it over for you. It will be well worth the couple of hundred dollars it may cost to possibly avoid thousands in the future.
Check out the local National RV owners club in your area. There are FMCA Chapters devoted to owners of National RVs all across the US. I am a member of The Dolphins, which is the original NRV club located in the Southwest. You can find links to other NRV clubs on The Dolphins Website. www,dolphinclub.com
Happy Trails!
Darryl