soft floor near slide edge

[buddy1]

Hi Folks, i am stumped on this soft floor issue on our 2014 keystone retreat park model. The area in question is at the edge of the main floor where the carpet starts and the slide rests there is a 8 inch approx. spot that runs about 3 ft in length that is very soft and it appears the carpet is the only thing preventing my foot from going thru and can easily twist your ankle if not careful, i am reluctant to cut open the carpet or try and lift it as i am not sure how it is secured especially at the raised part whenre the slide comes up to, i would have to replace the entire piece 14ft x 16 ", i cannot figure out how moisture is getting in this area,the spot is at the back end of the superslide.Any ideas would be greatly appreciated as i have searched the internet for months.you cannot see anything from underneath the RV and can't see how water could travel under the main structure, i had thought maybe during heavy rain the water would run down the side wall and creep under the framework but that doesn't make sense and the slide floor itself is solid.