Charley 67: I've been down your road many times and it is almost always a problem with the starter being shot or a low quality "life time" guaranteed rebuilt unit from an "xyzzy Auto Parts Store". This is, of course, assuming your battery isn't shot. Bite the bullet and buy a new quality built starter or a Ford factory rebuilt unit. Make sure , of course, that it's actually a Ford manufactured rebuilt and not some off branded thing that Ford sells.It's going to cost more but it'll be worth it.Just wanted to also say that you bought the rv used and the PO might have had starter issues previously and changed the starter and replaced it with some low quality unit.