I have had the camper parked for a good amount of time over the past couple of years....very minimal usage. Currenlty trying to sell it so making any small repairs and making sure there is no leaks. I have checked the roof and the sealant was good. I also checked the vent on the side of the camper and it was dry inside. I cut the bad piece of particle wood out and left it off for 2-3 weeks. I put paper towels all around it, inside the cabinets front and back and checked it, especially after rain storms and nothing. After additional research, humidity and not enough ventilation will do that to particle board over time. I replaced the wood and now have the windows and the 2 vents open. Thanks for the advice.