Yeah, I had soft spots on my Zinger and it turned out the cellar door seals were shot, let water in, and soaked the fiberglass insulation which in turn rotted the plywood flooring. I had to cut out a lot of flooring, remove all the water logged fiberglass and replace it all, including new flooring, vinyl, and I used spray foam insulation since it is fire resistant was well as repels water better then fiberglass. I also had to replace some of the framing. Good luck, but be prepared to do a lot of work!
2010 Zinger ZT29DS - SOLD
2021 Grand Design Reflection 315RLTS
2020 Silverado HD3500 Duramax