On the bottom corners of the cargo door, on the inside, are drain holes. Be sure that the draining system works well, nothing in there clogging.

I would remove the trim panel very carefully (may have water rot problems) and look into the door at that drain area. Clean it clear. Spray it with something protective.

All my 245s had the same problem, found usually when water drips on the back of the neck.

Never figured out where the leak was.

Good Luck,

Bob

:>)