underside of bedroom slide

[thompsons 369rl]

About 6 months ago I noticed an area on the underside of the bedroom slide (outer edge where the center roller rides) that was wearing through the black coating covering the OSB. The dealer said it was normal wear an tear and applied some tape over the area. No big deal, right? The tape finally came off and the area is worn much worse as well as being wet. One thing I know is OSB and water don't go well together and the moisture seems to be migrating along the outer edge of the area. I need some help here since, over time, the area seems to be getting soft and slowly coming apart. We are out of warranty by 3 weeks. See attached photo.

Thanks for any help you can offer.