Hi , we have just got ours back from dealer after some warranty work and they did a hab service while there got damp in rear locker door 36% and the next high reading is somewhere near the same place as op but looking at the diagram it seems to be in the same area under front bench seat with a reading of 21% will have to keep an eye on it and the joint in his picture , might put some silicone around it to see if it has any effect. imala730
I would not recommend Silicon for sealing a motorhome - something like Sikaflex should be better.