Note that the 33SW has a full-wall slide, and from pics I've seen of it used at dealers (the floorplan isn't currently on Thor's website) many of them didn't have the "3 Traxx" update.
I wonder if that would help out here.
Speaking of which, it looks like another 33SW owner had an issue in these very forums a couple of years ago:
http://www.thorforums.com/forums/f4/...blem-1275.html