One handy trick that worked for us was when we stopped at a fair on our trip. When we returned, the engine (rear diesel, class A) wouldn't start. In fact, we got nothing, not even a click or a moan. BCAA couldn't find us so we were on our own. A older guy (older than me...) came by, took his hammer and banged our starter. Bingo, we were up and running again. Apparently this was fairly common in the "old" days, esp for farmers. He said a rock or anything heavy will do. Haven't had any problems with it since but he suggested it would need to be replaced at some point.
Gary