We bought our Palazzo used with a little over 4000 miles from our local dealer. We have a little over 8000 miles and are heading to Maine for big repairs. The undercarriage of our unit has leaked during rain we encountered and is starting to rot. Of course, it is out of warranty. We are afraid of putting anything heavy in the storage because it might fall through the floor. Welcome to the world of Thor.
I would contact the Thor Service Center regardless, and tell them that you suspected this some time ago, but was not 'sure' what it was... they actually may give you lee-way toward this under warranty, as they did for us....replaced all the storage flooring in the Main and Wet full-thru bays.
two Campers, two Electric cars
former diesel pusher traveler