[Mikendebbie]

My J-panel popped out of the rubber "keeper" gasket along the top edge on one of our first trips in 2018. I saw it flopping in the mirror and fortunately there was a Walmart a few miles ahead. DW and I popped the panel back into the rubber gasket and I used silicone (its what I had on hand) to seal over the entire length of the gasket. No trouble since. For 2018 models - they were not using staples to attach the J-panels (at least none that I have found). My list of "things to do to the RV someday" includes adding a few braces to the bottom of J-panel (kicked back to the frame) to provide more rigidity and strength.

The sketch below IS NOT accurate for the actual construction - but it illustrates the gasket "keeper" at the top of the j-panel.

I recall that when I first posted about this problem - others had experienced the same thing. Also I remember several threads about putting a dab of silicone over the back side of the screws that hold the fender skirts on so that the screws wont back out of the skirt. I treated all of the fender skirt screws and any other similarly backed screws. I can't remember what those are called - but someone here will remember and provide a link to previous threads on the subject.