Manual

If you can't get a copy of the manual, don't fret about it too much. I don't know about Breckenridge in particular, but many RV owner's manuals are so generic and basic as to be of very little value. There are some exceptions, and some companies which provide very good maintenance information like wiring and plumbing diagrams, but the majority are rather poor. Usually the builders do include manuals and literature for the appliances and so forth that went into the RV, which are more helpful but can usually be found by searching for the specific appliance online.

There are a number of books written about basic RVing, along the lines of the Dummies Guides (and maybe even an actual one of those). If you're new to RVing and have general questions one of them would frequently be more useful than the actual manual from the manufacturer.