Mike, (Manchester, MD)
Mike, in some cases it is possible to place small shims under the bottom of the door frame creating a slight ramp downward and outward towards the exterior. Of course, this may also raise the bottom of the frame such that it will require an adjustment to the action of door closing. A careful inspection of the construction of the door frame from inside the coach will determine where best to place the shims. The shims should be aluminum so that any contact with moisture will not cause additional problems; I’ve used strategically placed aluminum washers in the past. And I would indeed double-check the integrity of that door seal. But I would wager it has more to do with the actual slope of the threshold itself.